Application of internal law by a state beyond its own territory is an extraordinary action in international law. It requires not only a solid justification but is also subject to many restrictions. It often comes to conflicts against this background that is why extraterritorial jurisdiction is considered as a dangerous but yet an effective instrument of foreign politics. The article not only provides a concise definitions of extraterritoriality but also points to its acceptable bases (liaisons) and restrictions. Moreover, a review of interesting, representative doctrine stances has been done. Controversies and dangers related to the discussed institution are explicitly emphasized. In contrast, the selected examples of conflicts resulting from extraterritorial application of internal law will be discussed in the upcoming second part of the reflections. The entire article is not meant to be a comprehensive overview but rather a basis for a more detailed analysis and discussion.