The publication addresses the cases decided by European Court of Human Rights where the Court obliged a Contracting Party to the Convention for the Protection of Human Rights and Fundamental Freedoms to obtain diplomatic assurances for a person who was to be deported to a third country. The author analyses recent case law of the Court, ponders over the effectiveness of the obtained assurances, and their place within the legal system. Doubts are cast over the fact that enforcement of the assurances in question adversely affects the principle of separation of powers (the executive power is obliged to influence court rulings). Despite those reservations, the author approves the idea of “diplomatic assurances”, while proposing the concept of “convention immunity” and recommending certain legal amendments to be introduced in the future, including the adoption of an additional protocol to the Convention.