Treason

Treason was a criminal offence of betrayal of one's nation, planet, or other state. The penalty for treason was commonly death.

The criminal Slitheen family were forced off their home planet, convicted of high treason, as well as fraud and theft, by order of the High Council of Raxas Prime. They were sentenced to death. (TV: The Gift)

During the Human-Hath War on Messaline, General Cobb ordered the Tenth Doctor and Donna Noble imprisoned after the Doctor objected to him using the Source to exterminate the Hath, refusing to allow them to "spread treason." (TV: The Doctor's Daughter)

Robert MacLeish objected to the Father Angelo's plan to overthrow Queen Victoria, branding it treason. (TV: Tooth and Claw)

Mavic Chen and his security chief Karlton were found guilty of high treason when a message recorded by Marc Cory revealed that the two men had been conspiring with the Daleks. The sentence was execution, although Chen was already dead when Diksen arrested Karlton. (PROSE: The Mutation of Time)