This article examines the state of international relations between the former Soviet republics post-1991 as structured within the Commonwealth of Independent States ("the CIS") in terms of their institutional elements and the key causal factors behind them. In doing so, it seeks to complement the existing research written predominantly out of binary or normative perspectives by accounting for the intricate mix between the legal and the political within and among the member states and by focusing on the functional value and rationality of the CIS in its current format. Using the conceptual framework of legalization of international relations for its analysis, the article reveals a complex picture of the relations within the CIS, whereby no single model but, rather, a set of institutional patterns or regimes can be distinguished. The analysis shows that these regimes are characterized by the prevalence of "soft" or "softened" (as opposed to "hard") legal institutions. The argument made here is that "soft" forms of integration offer specific advantages while mitigating some disadvantages of "hard" forms, particularly in relation to dealing with sovereignty sensitivities, uncertainty and complexity, accommodating diversity, and reducing contracting costs. In this sense, reforming the CIS can be better conceptualized in terms of finding the right mix between "hard" and "soft" legalization of its institutions to correspond to its needs and realities at this moment.