2036
According to Lt. Commander Data in the pilot episode of Star Trek: The Next Generation, this year the United Nations resolved that "No person shall be made to answer for the crimes of their race or forebears." The entity Q scoffs at this, saying this was a court of 2079, when the U.N. no longer existed. Complicating this argument is that the date of 2079 in Trek lore is 16 years after the events of Star Trek: First Contact, when extraterrestrial life has already been discovered and is assisting humanity to recover from the Third World War.