The flag of Montenegro was constitutionally sanctioned with the proclamation of the Constitution on 22 October 2007.

The flag of Montenegro (Montenegrin: Застава Црне Горе / Zastava Crne Gore) was officially adopted with the Law on the state symbols and the statehood day of Montenegro on 13 July 2004 at the proposal of the government of Montenegro. It It is a red banner with broader golden edges all around the red field with the coat of arms of Montenegro in its centre.

The Law on the state symbols and the statehood day of Montenegro reached full effect the day after its publication in the Official Gazette of Montenegro. The publication occurred 12 July 2004 and the legal power of the Law occurred the day after, on 13 July 2004 – the statehood day of Montenegro. Wikipedia