Introduction

Article 76 of the 1978 Spanish Constitution, found within Title iii regarding the General Courts, introduces for the first time in Spanish constitutional history the concept of Parliamentary Commissions of Inquiry, embedded within the tools of ordinary parliamentary oversight (García Roca, 1995; García Mahamut, 1996, 2011; Torres Bonet, 1998; Presno Linera, 1999; Lavilla Alsina, 2019). This article stipulates that these commissions may investigate “any matter of public interest” and can be established by either the Congress, the Senate, or jointly. Their regulation extends beyond the Constitution, as detailed in the content of Organic Law 5/1984, of May 24 (loci), Article 49 and subsequent articles of the Senate Regulations and Article 40 and subsequent articles of the Congress Regulations. In fact, Parliamentary Commissions of Inquiry are conceived as instruments for the General Courts to exercise oversight over governmental actions, in alignment with Article 66.2 of the Spanish Constitution (ce) and Article 29.2 of the Government Law. This oversight framework is replicated at the regional level as stipulated in Article 152 ce, enabling regional parliaments to scrutinize the actions and omissions of their respective governments. As well as this, there is a provision of criminal sanction in the case of non-appearance or lying during the investigation, aligning with the characteristic component of direct hearing (Martines, 2007, 211).

Nonetheless, there is a doctrinal debate regarding the classification of these commissions within parliamentary functions, including how they can invade the judicial power’s sphere during the development of their parliamentary works. Although their conclusions are not binding for the courts, the mandatory nature of appearances, the power to summon any citizen deemed relevant to the investigation, and the potential for their work to proceed in secrecy and concurrently with ordinary judicial activities grant them significant impact on the media agenda and public opinion (Aragón Reyes, 1986). The stc 77/2023, following statements made by stc 111/2019, points towards the necessity of establishing significant limitations on the nature and function of these commissions, emphasizing the protection of the fundamental rights of those investigated, particularly the presumption of innocence (Cobreros Mendazona, 2023; Marañón Gómez, 2023). This conception reinforces the need for a clear separation of powers and mandates that commissions must adopt procedures that respect basic procedural guarantees (Fernández Gutiérrez, 2024). Implementing this jurisprudence in parliamentary practice presents substantial challenges, such as regulatory reforms to ensure effective compliance.

Moreover, this issue is of critical significance for several fundamental aspects of democratic governance: the principle of separation of powers, the role of minorities and opposition, public confidence in parliamentary institutions and their oversight functions, especially in terms of effectiveness and reliability and, by extension, the preservation of democratic norms. It also bears implications for essential rights such as the presumption of innocence, especially at a time when trends towards the weakening of democracy and the rule of law are proliferating, including from the perspective of parliamentary procedures (Konrath, 2021; Pérez-Gabaldón and Hernández-García, 2023).

Methodology

This study aims to identify several critical gaps in the understanding and implementation of Parliamentary Commissions of Inquiry in Spain, including an ongoing scholarly debate regarding the classification and potential judicial encroachment of this instrument (Cobreros Mendazona, 2023), challenges in implementing recent jurisprudence in parliamentary practice, the need to balance parliamentary oversight with fundamental rights protection (Elena Griglio, 2020), and a lack of comprehensive understanding of Commissions’ impact on democratic governance.

To address these gaps, the study aims to make significant contributions through a combination of descriptive elements in explaining issues, such as the notion of parliamentary oversight or the presumption of innocence, a legal doctrinal approach, and a normative evaluation. It seeks to elucidate the role and limitations of Parliamentary Commissions of Inquiry within the Spanish constitutional framework, explore recent jurisprudential guidelines, analyze the impact these Commissions have on the separation of powers and fundamental rights protection, and examine their effectiveness as democratic oversight tools in the face of contemporary challenges to democracy and the rule of law. Moreover, this research is particularly pertinent given the current context of potential democratic erosion and the need to maintain robust parliamentary oversight mechanisms while safeguarding fundamental rights and the separation of powers, stating if Parliamentary Commissions of Inquiry in Spain effectively fulfill their constitutional mandate of oversight while respecting the separation of powers and protecting fundamental rights, particularly in light of recent jurisprudential developments and contemporary challenges to democratic norms.

Parliamentary Oversight and its Instruments: Spanish Commissions of Inquiry’s Case

Parliamentary oversight constitutes a fundamental function of the Spanish Cortes Generales, as established in Article 66 of the 1978 Spanish Constitution. This oversight is exercised through various mechanisms that enable the supervision and scrutiny of the Government (Zafra Valverde, 1973; Medina Rubio, 1994). Overall, oversight functions are categorized into two primary types: singular control and routine control. Singular control encompasses procedures such as the investiture process, motions of censure, and votes of confidence, while routine control includes instruments such as parliamentary questions, interpellations, and Parliamentary Commissions of Inquiry (Ruiz Robledo, 2006).

Moreover, the significance of parliamentary oversight lies in its capacity to maintain legislative independence and provide a forum for governmental critique. As Aragón Reyes (1986) and Rubio Llorente (1985) posit, this oversight is crucial to prevent legislation from becoming merely an extension of governmental will. Also, it has to be pointed that parliamentary procedures of control and information are directly related to the activity of political orientation (Martines, 2007, 208).

Theorically, the opposition exercises this oversight function with greater intensity, utilizing it not only to scrutinize the Government but also to present itself as a viable alternative (Pasquino, 1998). In fact, this aspect highlights the political nature of parliamentary oversight, although it does not preclude its susceptibility to legal analysis (Aragón Reyes, 1986). Developing this concept, García Fernández (1994, 42) conceptualizes parliamentary oversight instruments as the array of procedures and mechanisms at Parliament’s disposal to maintain and sustain the relationship of trust established with the Prime Minister or other government officials, which is something that can be achieved through continuous verification that the government is fulfilling the material objectives outlined in its program, as committed to by the governing body.

Considering this, authors such as Champagne (2007, 94) posit that the current manifestation of separation of powers tends to favor the majority, which can be bifurcated into two interconnected components: the governmental majority and the parliamentary majority. This conceptualization suggests that the governing majority not only directs executive functions but also exerts substantial control over legislative processes. Notably, this control extends to the ostensible opposition’s role, as the majority effectively manages parliamentary oversight mechanisms, including questioning procedures and the task of parliamentary committees. Due to this, it can be noted that parliamentary control has a diverse nature of oversight tools which help to fulfill the continuous process of verification and assessment that endures the fiduciary relationship between Parliament and Government, a connection which is characterised for the importance of information and oversight. It is important to reinforce that parliamentary investigation is not simply about collecting data and information, but rather aims to elucidate matters of public interest to subsequently offer an assessment thereof, albeit always limited to judging political acts (Blachér, 2005; García Mahamut, 2011).

The doctrinal polemic surrounding Parliamentary Commissions of Inquiry, a parliamentary figure of Anglo-Saxon tradition (Martínez Sospedra, 1994, 2007), revolves around the debate that these instruments, despite being traditional tools for gathering information on specific matters, lack punitive authority. This limitation extends to questions and interpellations, complicating their classification as instruments of parliamentary control, beyond the ambiguity of Article 76 of the Spanish Constitution on their specific nature. This gets more developed as Rubio Llorente (1993) contends that a connection between control and sanction is not necessary, a view supported by most of the Spanish constitutional doctrine where authors such as Aragón Reyes (1986), López Aguilar (1988), García Morillo (1994), García Mahamut (1996, 2007, 2011), Torres Bonet (1998), Navas Castillo (2000) or Marco Marco et al (2017). Moreover, the presented academical perspective challenges Santaolalla López’s (1982, 1984) argument that the inability to impose sanctions precludes classifying committees, questions, and interpellations as means of parliamentary control.

Overall, authors such as professor García Fernández (1993) characterise Parliamentary Commissions of Inquiry as parliamentary control instruments that, while providing an immediate evaluative effect on government action, lack material consequences. Their purpose is to render a value judgment on governmental actions while having, as García Mahamut (2011) points out, the originality of the provision, according to Article 76.2 of the Spanish Constitution, of the mandatory nature of attendance. Also, these committees trace their origins to Inquiry Commissions, reflecting the historical tension between legislative and executive branches (Tardieau, 1937; Bidegaray & Emeri, 1973; Torres Bonet, 1998, Fernández Sarasola, 2000).

Montero Gibert and García Morillo (1984) assert that the function of these Commissions is fulfilled by providing the controlling entity with the necessary basis to form an opinion on executive performance. The conclusions of a Parliamentary Commission of Inquiry, due to their political nature, represent parliamentary truth rather than social truth. Moreover, Pérez Royo (2003) notes that while parliamentary truths carry political effects and potentially broader social reach, judicial function defines social truth in cases of rights violations or legal disputes.

In essence, Parliamentary Commissions of Inquiry derive their significance not from punitive capabilities, but from their regulatory authorization to submit conclusions for plenary debate. This process enables a judgment of the government that impacts the trust and responsibility link between executive and legislative branches. Giménez Martínez (2015) emphasises that these Commissions allow Parliament to exercise its control and information functions, deploying special powers over matters of public interest and scrutinizing executive actions and omissions.

Thus, the recognition of judicial or quasi-judicial powers to gather evidence enables this parliamentary entity, which is ad hoc and characterised by its temporary nature, to fulfill the parliamentary mandate of investigation (Torres Muro, 1998). This investigative function, from the perspective of rationalized parliamentarism, aligns with the functions traditionally attributed to Parliament: legislative functions, political orientation, and oversight. The latter is particularly significant in contemporary pluralistic democracies, not only for scrutinising the Executive branch but also for shaping public opinion and facilitating political alternation (García Mahamut, 2011, 259).

Requirements for Establishing Parliamentary Commissions of Inquiry

It must be noted that the Spanish model distinguishes itself from other systems through its unique approach to investigative interventions based, precisely, on its material requirement. This distinctive feature is exemplified by the possibility of two potentially concurrent procedures: one of a judicial nature and one of parliamentary origin. The demarcation between these spheres is determined by their respective inherent characteristics and objectives (Massa, 2003, p 110–112), so this framework allows for parallel investigations into matters of public interest, conducted simultaneously by both judicial and parliamentary bodies. In a nutshell, the Spanish model institutionalises a dual-track approach, where the boundaries between judicial and parliamentary inquiries are defined by the intrinsic nature and purposes of each investigative process, parliamentary or judicial. Such a model reflects a nuanced understanding of the multifaceted nature of public interest investigations, acknowledging that different institutional perspectives may contribute valuable insights. In sum, by allowing for this procedural duality, the Spanish system potentially enhances the comprehensive examination of complex issues, while maintaining the distinct roles and competencies of judicial and parliamentary bodies.

However, Article 76 of the Spanish Constitution does not present an exposition of motives that specify the initiation of an investigation: quite the opposite, as it is more explicit in making clear that the conclusions of a Commission are not binding for the judicial sphere, nor should they affect it in terms of its resolutions. In synthesis, the ultimate objective would be an evaluation of the management of public powers (Gude Fernández, 2000; Holgado González, 2008), giving rise to a political assessment of the decision-making of those responsible for political management in order to, as García Mahamut (2007, 49) explains, illuminate a recommendation about what measures should be adopted to prevent the recurrence of situations that can range from a terrorist attack of utmost gravity to a very significant case of corruption.

According to Pérez Royo (2003), the 1982 Rules of Procedure of the Congress of Deputies has adopted a restrictive approach regarding these committees, linking their creation to the existence of a favorable parliamentary majority. This implies that the decision to establish such committees falls on those who will be the subject of investigation. Therefore, Article 52 of the Congress Rules regulates investigation committees, modified in 1994 to address their publicity. This reform also affected Articles 63 and 64, establishing the publicity regime for Plenary and Committee sessions, including information provided to investigation committees. According to Article 64.4 rc, sessions are not public, with data and reports being confidential when so stipulated by the Constitution or law, although accredited media representatives are allowed access to non-public sessions. Therefore, the initiative to establish a committee, according to Article 52.1 rc, can come from the Government, the Bureau, two parliamentary groups, or one-fifth of the Chamber, subsequently requiring approval by the Plenary. The committee’s functioning is regulated in Article 52.2 rc, which establishes the elaboration of a work plan, appointment of rapporteurs, request for testimonies and decision-making by weighted vote.

In addition, the Spanish Senate’s Rules of Procedure delineate a comprehensive framework for establishing investigation committees (Jiménez Campo, 1987), with Article 59 serving as cornerstone by permitting their creation to scrutinise matters of public interest. This process can be initiated either by the Government or through a collective effort of 25 Senators from diverse parliamentary groups. Once set in motion, Article 52 imposes a stringent timeline, mandating committee constitution within a mere ten days post-member designation, followed by the crucial election of a Bureau as stipulated in Article 53. Article 60 further refines the operational aspects, necessitating the development of a detailed work plan replete with deadlines, while simultaneously obligating regular progress reports to the Bureau. Notably, this article also confers upon investigation committees the significant power to summon citizens for testimony, a provision reinforced by Article 76.2 of the Constitution. The culmination of these efforts is addressed in Article 60.3, which mandates the publication of committee conclusions, with Article 60.5 allowing for their communication to the Public Prosecutor’s Office.

Regarding autonomous parliaments, the 1978 Spanish Constitution attributes the control of autonomous governments to the parliaments of the Autonomous Communities through Article 152 ce. However, not all statutes of autonomy make specific reference to investigation committees, with their development varying between statutory and regulatory levels depending on the autonomous community. A common feature in all autonomous approaches is the parliamentary control of the actions and omissions of autonomous governments orientation of investigation committees, understanding the executive as a power subject to legislative control, as mentioned by Lavilla Alsina (2019) or Lucas Murillo de la Cueva (1986).

Finally, as a clarifying point, scholars such as Pace (1973, 103), Ardant (1995, p 551–552) or Di Ciolo and Ciaurro (2003, 608), contend that the establishment of a parliamentary investigative committee is not primarily motivated by a desire for information-gathering. Rather, it is posited as a strategic maneuver aimed at undermining political opponents through the exploitation of events that capture media attention and public interest. In sum, this political strategy would be ultimately manifested in the creation of such parliamentary commissions. Nonetheless, this analysis implies that the ostensible function of these committees, understood as the activity of gathering information and conduct inquiries, may be secondary to their role in political maneuvering and public relations. Still, it is evident that this interpretation highlights the complex interplay between parliamentary procedures, political strategy, and media dynamics in contemporary democratic systems.

Functions and Limits

The material limitations on parliamentary investigation that are directly derived from other mandates codified in the Spanish Constitution are found in the actions of constitutional bodies or those of constitutional relevance, in the exercise of competencies attributed through the Constitution, in law, or statutorily (Amorós Dorda, 1989; García Mahamut, 2011, 261).

In the Spanish legal system, Parliamentary Commissions of Inquiry are granted a series of extraordinary faculties to enable them to develop their investigative mission for the exercise of the parliamentary oversight function that justifies their existence. Firstly, Article 76.2 of the Spanish Constitution grants the power to require the mandatory appearance of any citizen before the Committee that requires it. This committee is regulated by the content of Organic Law 5/1984, of May 24 (loci), which emphasizes the mandatory nature of appearance in its article 1.1.

Due to this, it is crucial to first briefly examine the provisions of Article 76 of the Spanish Constitution to understand two key points highlighted by García Mahamut (2007, 52); the investigative capacity granted to these parliamentary bodies does not constitute an independent function separate from those already assigned to Parliament, because parliamentary investigation should be understood as an extension of Parliament’s general functions, particularly with respect to political oversight; Parliamentary Commissions of Inquiry are entities of a strictly political nature, as the constitutional article itself establishes a clear distinction between the purposes of judicial proceedings and the objectives pursued by parliamentary investigation.

Secondly, and in relation to the first faculty, it implies a capacity to sanction, through criminal channels, in two different but potentially complementary ways: criminal sanction for non-appearance before the Committee as provided for in Article 502.1 of the Criminal Code, and criminal sanction for failing to tell the truth according to Article 502.3 of the Criminal Code.

Lastly, there is the faculty to conduct parliamentary investigations in parallel with judicial processes. This possibility, which does not exist in neighbouring legal systems, such as the French model, is possible thanks to the constitutional provision that establishes the conclusions of Parliamentary Commissions of Inquiry as non-binding for the judiciary. In fact, the Spanish Constitution itself exclusively reserves the exercise of jurisdictional power to Judges and magistrates. This excludes, in evident adherence to the classic Montesquieu’s (1995) doctrine of separation of powers, the legislative and executive powers from exercising judicial faculties. This logically also excludes the Committees, precisely because this delimitation between the sphere of legislative and judicial power is theoretically concretised through the provisions of Articles 76 and 117 of the Spanish Constitution. In practice, as García Mahamut (2011) or García Fernández (2023) point out, it can tend towards a praxis that is detrimental to fundamental rights due to the lack of specific normative regulation.

At this juncture, it is crucial to remember that Parliamentary Commissions of Inquiry are not courts of law, and consequently, their members are not judges belonging to the Judicial Branch, nor are they presumed to possess the independence, immovability, and subjection to the rule of law characteristic onto the judiciary. Instead, the members comprising these Committees are representatives of specific political factions, primarily bound by a fiduciary relationship with their electorate: here emerges the significance of parliamentary roles in conjunction with institutional architecture (Bates, 2021). This connection, which compels them to demonstrate the efficacy and utility of their parliamentary work to their constituents, aims to oversee governmental action. Nonetheless, this does not preclude these Committees from being endowed with extraordinary powers within the legal framework, as provided by the 1978 Constitution itself, indirectly through sanctions stipulated in the Penal Code, and in detail by the Organic Law 5/1984 of May 24 (loci).

Despite these substantial capabilities, it is equally true that Investigative Committees face limitations, notably in the non-binding nature of their rulings and the separation between parliamentary and judicial activities as delineated in Article 76 ce. From this, García Mahamut (2007, 55) infers a dual limitation, predicated on procedurally dissociating parliamentary from judicial proceedings due to their divergent objectives. On one hand, this constrains the Committees’ investigative activities to the purely political sphere, while on the other, it simultaneously requires the Courts to ensure that their judicial resolutions remain unaffected by any conclusions the Committee might reach.

In terms of comparative law, the German case (Untersuchungsausschusse) significantly differs from the Spanish approach, particularly in the role it assigns to the parliamentary minority and in its judicial-like attributions. While the Spanish legal system does not explicitly recognise the creation of Investigation Committees by the parliamentary minority, this provision exists in the German case, where the control authority is unambiguously attributed to the minority. In the case of Italian Inchieste, these possess an instrumental configuration, oriented towards facilitating the achievement of political guidance and control functions, in addition to the legislative function. In other words: unlike the German case, which is more focused on pure parliamentary control, the Italian configuration is more oriented towards acquiring elements directed at legislative work, having the same powers and limitations regarding their capacity to inquire and investigate as judicial authorities, always confined to their specific subject matter and without the possibility of extensive interpretations (Di Ciolo and Ciaurro, 2003, 609). However, as García Mahamut (2011, 261) explains, the fact that the Spanish constituent opted for a non-judicialised model of Investigation Committees excluded the possibility of them having powers analogous to judicial authorities. This is particularly evident in Spanish Investigation Committees, which unlike their German and Italian counterparts, cannot conduct home searches, summon witnesses, or obtain documents through typical judicial channels.

Another noteworthy comparative case is the French system, which, in its recognition of the right of parliamentary investigation, encompasses the capacity of parliamentarians to seek and obtain information through parliamentary instruments, such as questions and committees. With its praxis directly regulated through Article 6 of the Organic Law relating to the functioning of parliamentary assemblies and by parliamentary regulations due to the lack of constitutional provision, they also cannot have decision-making power but rather, as in the Spanish case, can issue a report from which a declaration of judicial investigation action could be initiated if the necessary indications were present. Thus, it is understood that the function of this instrument is to gather information on specific facts, aspects concerning the management of public services or national companies, with the exception that, unlike the Spanish case, they cannot occur in parallel with open judicial cases. However, the hearings are public, and there is strong criminal provision to protect the secrecy of their work, at least until the issuance of the final report, which is usually published unless a vote of the Assembly decides otherwise. As a detail, this derived report usually reflects most of the committee members, with minority observations reserved for an annex (Burdeau, 1995, p 601–604; Acquaviva, 2005, p 195–197; Blachér, 2005, 220).

Finally, regardless of whether they are permanent parliamentary committees or not, it is evident that parliamentary control mechanisms in Europe are generally less effective compared to the Anglo-Saxon model. This is due to several factors: the strong party discipline prevalent in European parliaments, which constrains independent action; the lack of quasi-judicial powers for the Parliament, leading to a deficiency in resources and means; and restrictive regulations that limit the obligation of officials to appear before committees. Although this is not the case in Spain, in countries like France and Belgium the absence of a legal obligation to appear undermines the authority of these committees. Lastly, the fact that many committees are established on an ad hoc basis directly impacts the thematic preparedness of their members and the continuity necessary for effectively investigating complex issues (Martínez Sospedra, 1994, 2007, p 547–549).

Commissions of Inquiry and the Judicial Sphere

The separation of powers does not entail an isolated functioning of these powers (Martínez Elipe, 2000, 454), given that politics and law are distinct yet osmotic phenomena. This is even more apparent when considering the non-watertight nature of the separation of powers—or rather, functions—and the unifying vocation of politics, which often finds itself in a subordinate position to constitutional norms due to its preexistence to law itself. Consequently, in this particular case, the existence of a balance between parliamentary autonomy and other constitutional principles proves fundamental in any parliamentary system (Albanesi, 2022).

In the Spanish context, the interaction between judicial functions and parliamentary investigations is governed by the principles of compatibility, non-interference, and collaboration: the objective is to oversee governmental action, not to initiate a process capable of administering justice. However, García Mahamut (2007, 47) notes that the relationship between judicial and parliamentary investigations is often characterized by overlaps and frictions. This situation is exacerbated by the tendency to use judicial bodies to supplant Parliament in politically relevant matters. García Morillo (1997, 89) warns about its effect: political responsibility is frequently activated only after a judicial verdict, suggesting a subordination of political action to the judicial determination of a criminal offense.

Conversely, it is also plausible that such a Commission may be designed to obtain a political judgment and, consequently, a political verdict that diverges from the judicial one or aligns with the strategic interests of the majority that initiated the parliamentary process for that specific Commission. This possibility is further reinforced by the fact that those conducting the investigative work are not, as previously emphasised, judges, but rather elected politicians whose legal training and knowledge, particularly in terms of protecting the most fundamental rights and liberties, is presumed to be limited.

Thus, an undeniable risk is that, while political accountability is the only form of responsibility that Parliament can demand, the occurrence of situations within an Investigative Commission where their elucidation transcends political sanction and reaches the criminal sphere generates interferences which, as Caamaño Domínguez (1994, 154) maintains, can mobilise public opinion and, consequently, influence the judicial investigation on the same matter. Furthermore, a third possible scenario is also significant: the coexistence of a judicial process and an Investigative Commission, conducting their work in parallel and addressing the same case, each within its respective responsibility sphere.

However, the status of those investigated in parliamentary Commissions bears significant similarities to that of defendants in criminal proceedings, as noted by Gude Fernández (2000, 40) and García Mahamut (2007, 72). Nevertheless, this similarity is not fully reflected in the rights and protections afforded to individuals appearing before these commissions. Ideally, any person summoned to testify should be surrounded by a comprehensive set of rights and guarantees during their involvement with the Commission. Moreover, should the findings and documentation obtained during the investigation be utilised as evidence in a criminal process, the witness must be granted full rights to defense and the opportunity to present arguments. Nonetheless, the current reality falls short of this ideal scenario, highlighting a discrepancy between the theoretical protections and the practical application of these rights in parliamentary investigations.

Furthermore, it should be considered that if, in addition to being involved in judicial proceedings, individuals are compelled to appear before a Parliamentary Investigative Committee, the safeguarding of their right to remain silent and not to incriminate themselves requires the interpretation that it is not feasible to impose the provisions of Articles 502.1 and 502.3 of the Criminal Code as the obligation to testify and to not provide false testimony before the Committee directly conflicts with these protected rights.

In the context of potential parallel activities between judicial proceedings and parliamentary investigations, several scenarios warrant consideration. One such scenario involves the continuation of a political inquiry by a Parliamentary Commission even after the conclusion of a judicial investigation. On the contrary, a judicial conviction might diminish the significance of a parliamentary investigation. As García Morillo (1998, 108) observes, a judicial acquittal potentially creates a window of opportunity for the Parliamentary Commission to further pursue its inquiry. Moreover, García Mahamut (2007, 73) posits that judicial absolution does not preclude the possibility of political accountability, opening a perspective that highlights the distinct nature of political and judicial responsibilities: the interplay between the principle of res judicata and the doctrine of ne bis in idem may create a unique circumstance. In this scenario, individuals possessing pertinent information may be more inclined to disclose it to Parliament, cognizant that such disclosure no longer carries the risk of criminal consequences.

Besides, despite differences in principles and powers regarding judicial investigation, and although judicial instruction does not preclude the establishment of Parliamentary Commissions of Inquiry, the practice of these committees raises concerns about respecting the declaration of proven facts made in judicial rulings. This extends beyond the fact that res judicata is not exempt from political evaluation precisely because of its nature (Martínez Elipe, 2000, 457–458). Concurrently, another aspect for discussion relates not to facts already adjudicated, but to the respect for the presumption of innocence, whether judicial proceedings are underway or not.

At this juncture, it is important to mention the need for modification in conflicts between organs when material situations of defenselessness are detected, which tend to recur. Thus, it is imperative to prevent material situations of defenselessness and to ensure the validity of constitutional guarantees in such a manner that the legal consciousness that allows us not to abdicate from these is not lost. The genuine challenge lies, as well, in averting jurisdictional oversight that severely impedes the execution of functions ascribed to the parliament, resulting in a mechanism incongruous with the systemic rationality of the three branches of government and incompatible with the coexistence of judicial review and parliamentary action (Da Silva Ochoa, 2007, 145; García Roca, 2007, 101).

Regarding the presumption of innocence, this is a right originally conceived as a guarantee of personal liberty against the state’s ius puniendi, present in the 1789 Déclaration, in American declarations of rights, and, naturally, in the Spanish legal system through Article 24 of the Constitution. It has been recognised by the Constitutional Court as a fundamental right, binding on public powers due to the requirement of superior constitutional norm (Fernández Montalvo, 1990, 61; Ovejero Puente, 2006, p81–83), a fact reinforced following the Constitutional Court Ruling 31/81 of July 20, 1981. This positions it as a fundamental right and, simultaneously, distances it from being considered a general principle of law or a procedural guarantee.

Nevertheless, Ovejero Puente (2006, 96) is clear: the operation of the fundamental right within the evidentiary system, as defined by law, is not equivalent to the legal configuration of said right. This is complemented by the conception of the right to effective judicial protection as the matrix of the rights enshrined in Articles 24.1 and 24.2 of the Constitution, while also extending the constitutional protection of the right to its extra-procedural aspect, that is, to the sphere of interaction of Parliamentary Commissions of Inquiry. As a salient point, this provides even greater significance when considering that the testimony dispensed may be utilized against the declarant in criminal proceedings. Consequently, the charter of rights applicable to those appearing extends to encompass the right to remain silent as enshrined in Article 16 ce, the rights consecrated in Article 18 ce, and the right against self-incrimination, an extension particularly pertinent given the absence of any legal precept that penalizes silence. Therefore, as García Mahamut (2007, 72) points out, it would be advisable to reflect on the appropriateness of legally predetermining the criminal value given to statements made before this parliamentary committees.

A clear illustration of this perverse deviation in the practice of parliamentary investigation can be observed in the stc 77/2023: this case highlights the attribution of criminal responsibilities, violating the right to presumption of innocence. Furthermore, verdicts suggesting culpability were issued without judicial sentencing, negatively impacting the reputation of those summoned, all this occurring without procedural guarantees, legality, and proportionality, ultimately infringing upon fundamental rights. Moreover, the media dissemination of leaked information can potentially cause irreparable damage to the honor of those appearing before the committee. Additionally, these commissions may exceed their investigative scope, affecting individuals who are not even within the purview of the investigation (Marañón Gómez, 2023).

Finally, a theoretical solution proposed is for the committees to restrict themselves to describing facts, refraining from making judgments about culpability or potential criminal offenses, as this falls within the purview of the judiciary, as this self-restraint may prove challenging to maintain in practice, particularly when describing facts that could constitute criminal activities; A more radical response would be to suspend the parliamentary investigation at the first indication of criminal activity and refer the matter to criminal jurisdiction, or to prohibit the formation of investigative committees when judicial proceedings are already underway (Cobreros Mendazona, 2023).

The Role of the Minority in Parliament

Another important point is about parliamentary opposition, which plays a crucial role in ensuring the quality of democracy, as it is expected to provide a credible alternative to the governing majority. This capacity for effective opposition is essential, as it allows for critical scrutiny of governmental actions and the presentation of alternative policies (Pasquino, 1998). Still, while the opposition must engage with the majority to exercise its functions, it is not solely dependent on them for its role. Dahrendorf (1988) emphasises the importance of finding appropriate institutional expressions for opposition during transformative periods, highlighting the need for adaptable institutional channels. Furthermore, Pasquino (1998) asserts that improving political quality requires enhancing institutional structures underlying parliamentary and governmental operations. If so, a responsible opposition must recognise social fragmentation’s threats while maintaining its electoral power to effectively challenge the government. Ultimately, a strong opposition contributes significantly to a well-functioning democracy by promoting accountability and transparency within government.

Despite that, the conceptualisation of parliamentary oversight and the determination of its ownership present significant complexity in contemporary constitutional theory. Although the parliamentary opposition plays a fundamental role in scrutinizing governmental actions, it cannot be categorically stated that it is the sole holder of the control function. This perspective is grounded in several key aspects of the legal framework and parliamentary structure.

Firstly, it is crucial to note the absence of explicit legal recognition that exclusively assigns the control function to the opposition; the legal framework does not establish a clear distinction that grants this prerogative solely to opposition forces. Secondly, the attribution of parliamentary control is carried out organically, meaning it is conferred upon Parliament as an integral institution, without distinguishing between the various factions that comprise it. This approach emphasizes the conception of the legislative body as a unified entity in exercising its control functions. Furthermore, it is essential to understand that the active subject of the control function is Parliament as a whole. This holistic view reinforces the idea that control is not an exclusive prerogative of a specific sector within the legislative body but rather a shared responsibility among all its members.

However, it is important to clarify that the practical necessity of having majority parliamentary support to implement certain control mechanisms does not imply that this function is exercised exclusively by that majority. Parliamentary control, understood as political oversight (Aragón Reyes, 1986), should be seen as a collective responsibility involving all members of Parliament, regardless of their political affiliation or position regarding the government. This interpretation promotes a more comprehensive approach to parliamentary control, recognising that both the majority and the opposition play crucial roles, albeit potentially differentiated, in the process of governmental oversight. It reflects the inherent complexity of parliamentary dynamics and accentuates the importance of maintaining a balance among diverse political forces to ensure effective and democratic control over government power.

In terms of constitutional foresight, Spanish commissions do not entail a recognition of the parliamentary minority’s right to create such bodies, as is the case in Germany. This lack of recognition for minorities aligns the configuration with the Italian case and is confirmed following the reform of Article 52 of the Rules of Procedure of Congress (rcd) on June 16, 1994. It deepens doubts about the effectiveness of the instrument, considered by authors like Tosi and Mannino (1999, 393–394) as a tool governed by the majority, granting it an extraordinary nature precisely due to the empowerment it provides to the majority in the chamber (Santaolalla López, 1982, 249). In fact, the only exception favorable to the minority is that a reinforced minority can demand the creation of a commission, although its realisation depends entirely on a simple majority. The flaw, as noted by García Mahamut (2002, 31), is evident: the approach adopted by our legislator implies that in governments supported by an absolute majority, the possibility for the minority to activate this inspection mechanism is removed. Furthermore, this is compounded by the procedural logic that, during the investigative process, the minority lacks the factual capacity to exercise effective parliamentary oversight.

The legal recognition of the parliamentary opposition’s right -often the minority- to establish investigative committees, aimed at exercising effective parliamentary oversight, requires a balance with the parliamentary majority’s prerogative to adopt decisions by simple majority. This balance would not be infringed if such recognition were stipulated in a two-stage process: first, in the approval of the committee’s report, and second, in the conclusions adopted by the plenary session. Furthermore, this approach gains significance when considering, as García Mahamut (2002, 47–48) suggests, that Parliamentary Commissions of Inquiry are not inherently investigative in nature but rather decision-making bodies. Consequently, it is valid to delineate specific areas for their creation and internal operation without compromising the democratic functioning of the parliamentary institution.

As such, this would be plausible to mitigate a configuration that, according to Medina Rubio (1994), is among the least considerate of parliamentary minorities. Finally, it would also address the negative impact this configuration has on the oversight function of this parliamentary instrument and, ultimately, on its very inherent purpose (Embid Irujo, 1992; Presno Linera, 1999).

The Position of the Spanish Constitutional Court

In recent times, the Spanish Constitutional Court has ruled, to varying degrees, on aspects directly related to Parliamentary Commissions of Inquiry and their limitations. Consequently, the stc 88/2012, of May 7, recognises the fit of Parliamentary Commissions of Inquiry within the function of parliamentary oversight of the Government, framing all the faculties of deputies within the right of political representation, excluding from its scope matters of strict private interest (González del Campo, 2019). Continuing this line of delimitation, the stc 133/2018, of December 13, clarifies that parliaments cannot make judgments of political expediency, nor can they supplant judicial truth. Additionally, the ruling reminds that the conclusions of the committees are not binding.

Carrying on along this line, the stc 12/2019, of January 28, clearly states that all requests for committee complaints are protected by the right of political representation, as already indicated by stc 88/12, a right that allows their creation and drives their activity. Also, stc 111/2019, of October 2, establishes significant limitations on regional Parliamentary Commissions of Inquiry: the Court annulled the resolution of the Parliament of Catalonia that sought to investigate the monarchy, arguing that it exceeded regional competencies and violated the inviolability of the King as established in Article 56 ce. In fact, the ruling emphasises that regional committees cannot politically control state institutions or attribute criminal responsibilities, as these are functions reserved for judicial bodies. Furthermore, it highlights the necessity of respecting citizens’ fundamental rights during parliamentary investigations, providing a judgment reinforcing the separation of powers and the protection of the monarch’s figure, limiting the scope of investigative committees to prevent abuses and ensure respect for the constitutional order (Pascua Mateo, 2020).

Finally, the stc 77/2023, of June 20, which authors such as Marañón Gómez (2023) have labeled as the coup de grâce to investigative committees, details and delves into the limits of the committees and offers a significant change in the court’s stance. In sum, the ruling allows for the coexistence of a parliamentary committee and a judicial process. Likewise, the legislator can limit or restrict, by law, this coexistence without there being in any case interference between both processes. Thus, the key lies in the differentiation between political investigation, which settles responsibilities in the management of matters of notorious public interest that it investigates, and a judicial process in charge of matters relating to administrative regularity and the commission of crimes (Massó Garrote, 2001).

Therefore, it seems logical to affirm that if this latter scenario is brought to the forefront of a parliamentary investigative committee, there is an obligation to refer it to the court, a fact that contradicts focusing on it in parliamentary settings precisely because the management of an issue can only be settled there to clarify whether it has been deficient or not. Continuing with the analysis, another fundamental detail that emerges from the stc 77/2023 is that, while every summoned citizen has the right to appear, they should only do so regarding political responsibilities.

However, what is truly striking about the stc 77/2023 is the jurisprudential change for when the committee attributes, in the development and conclusions of its work, a punishable conduct: if this limit is transgressed, the right to the presumption of innocence is violated. In fact, this determination expands on the position that the Spanish Constitutional Court holds in relation to the limits when parliamentary autonomy is affected, overcoming a constant of self-restraint, and opting for the protection of individuals’ rights against overreaches of parliamentary investigations. Nonetheless, the standard that Spanish Constitutional Court adopted is the European one, characterized by the ambiguous jurisprudence of the echr as the main actor in the inclusion of presumption of innocence, as the case Rywing versus Poland, 18th February of 2016 stated, having the Venice Commission of the Council of Europe as amicus curiae whose opinion is reflected in the mentioned case and goes beyond the sentence’s development (Cobreros Mendazona, 2023). Anyway, the extra-procedural dimension of the presumption of innocence extracted from the echr jurisprudence goes beyond what tfeu displays, and as some authors as Cobreros Mendazona (2023, 57) stated, can differ from what Spanish Constitutional Court sometimes has expressed.

Conclusions

In contemporary European parliamentary systems, a discernible trend is emerging wherein executive branches are exerting increasingly substantial control over legislative processes, thereby diminishing the efficacy of parliamentary bodies (Griglio, 2020). This shift in the balance of power is particularly noteworthy in the context of Parliamentary Commissions of Inquiry: these commissions, designed as mechanisms for legislative oversight, are inherently structured in a manner that typically places them under the purview of the parliamentary majority. Consequently, this arrangement potentially compromises their intended function as independent investigative entities, raising questions about the robustness of checks and balances within these democratic systems. This not only hinders their ability to serve as a counterbalance and monitor the Executive but also relegates the parliamentary minority, and consequently the various forms of opposition to the chamber’s majority, to a residual position. In this circumstance, they can neither initiate the creation of a committee independently of the majority’s will or oppose the establishment of committees outright.

Continuing with the specific mechanism of creation and the general configuration of this parliamentary figure, favoring majority, one must add its array of competencies which, due to malpractice, often end up encroaching the sphere of judicial power and infringing upon individual rights. In this regard, the possibility of judging facts parallelly to the judicial system—facts always limited to the material requirement of public interest—makes sense due to the theoretical presumption that only political responsibility is settled in parliamentary settings, while its non-binding conclusions result in a truth of identical nature. However, the exceptional nature of mandatory appearance and the obligation of not providing false testimony, with penal provisions included, cannot foster a violation to the presumption of innocence of those investigated, generating alternative verdicts to those that would be guaranteed by an appropriate judicial process. This becomes even more significant when considering the enormous media impact and potential of this parliamentary figure and, consequently, the inclination towards the perverse use of its faculties. That is, its employment as a weapon of political opportunity.

Thus, all of this becomes even more notable when considering the recent pronouncements of the Constitutional Court regarding the scope and limitations of Parliamentary Commissions of Inquiry. These rulings clarify that being part of the set of ordinary parliamentary control mechanisms does not enable the making political judgments that replace judicial truth, and that special respect must be given to individual rights, not trampling them in the name of the right of representation, parliamentary autonomy, or, ironically, democracy. In essence, the effective fulfilment of the mandate entrusted to this parliamentary oversight tool is significantly challenged on three main fronts.

1. 1.There is the evident capacity, already cautioned by the Spanish Constitutional Court, to encroach upon the judicial sphere and issue parallel judgments that compete with or supplant judicial truth. These judgments are typically swifter in their resolution and garner greater media impact.
2. 2.This approach directly affects individuals’ rights, with the infringement of the presumption of innocence being the second factor that calls into question whether Parliamentary Commissions of Inquiry are fulfilling their role or overstepping their bounds. The European standard established by the ECtHR regarding the impact on the presumption of innocence in parliamentary proceedings does not ameliorate this situation, with jurisprudence that has been ambiguous at best since Rywin versus Poland (18 February 2016).
3. 3.The very mechanism of creation, directly dependent on the majority, diminishes the commissions’ investigative efficacy while significantly reducing the capacity of the parliamentary minority. This not only decreases the effectiveness of the parliamentary body itself but also dilutes the democratic checks and balances related to parliamentary control mechanisms, relegating various forms of opposition to the parliamentary majority to a residual position.

Consequently, Parliamentary Commissions of Inquiry in the Spanish case should be subject to reform. Such a reform should not only enhance their capacity to monitor Executive actions independently of the parliamentary majority’s will but also seek a model that better protects the presumption of innocence of those under investigation without compromising investigative powers. Also, it should aim to better align political inquiries with judicial processes, a consideration of particular importance in times of political polarisation and crisis of the rule of law.