According to one account, the Tribunal was the Gallifreyan body which prosecuted "temporal transgressions". As demonstrated when they obliterated the War Lord and condemned the Doctor to exile on Earth following the War Games affair, (TV: The War Games) they had the power to condemn transgressors to temporal erasure or to exile on Sol 3. Receiving such punishments from the Tribunal was one of the risks inherent in temporal tourism by other time-travellers who wanted to visit Gallifreyan history, although the activity nevertheless became relatively popular. One tour operator included in their terms and condition that they could not be held responsible if a temporal tourist was indeed prosecuted and condemned by the Tribunal. (PROSE: Gallifrey: A Rough Guide)
However, in other accounts, there were many other proposed identities for the court that tried the Second Doctor. (PROSE: Doctor Who and the Doomsday Weapon, The Trial of Doctor Who, The Infinity Doctors)