The thesis answers the question "How does the change in effective control affect investment protection mechanisms in the Ukraine - Russia BIT against the temporal scope of when investment was made?". The essence of the Tribunal's jurisdiction, territorial and temporal scope of the Ukraine - Russia BIT were analyzed according to the rules of Vienna Convention on the Law of Treaties. Relevant case law, doctrine and available information on the awards in "Crimean cases" were also parts of the analysis. A conclusion was made that changes in effective control activate BIT protection for Ukrainian investors in Crimea against actions of Russian Federation. As a result, investment arbitral tribunals have jurisdiction in cases where investment has not been initially made in the territory of the host state. The date of Russian Federation consent to arbitrate with Ukrainian investors in Crimea is the date of actual change in effective control.