MOSCOW — A Russian court in the contested Crimean peninsula sentenced a minority Tatar politician to eight years in prison on Monday, in a trial that his lawyers and human rights organizations called a sham.

Akhtem Chiygoz, 52, a former deputy head of the assembly that represented the Tatars when Ukraine controlled Crimea, was found guilty of inciting mass riots, specifically a large rally in February 2014 protesting the Russian presence in Crimea.

Nikolai Polozov, the renowned Moscow lawyer who served as Mr. Chiygoz’s lead defense attorney, said the sentence by the Crimean Supreme Court was “unlawful” on numerous grounds. Most important, he said, was that Crimea was part of Ukraine, not Russia, at the time of the protest that Mr. Chiygoz was accused of inciting, and that Russian law therefore did not apply.

In an interview, Mr. Polozov called the sentence “politically motivated,” and said it was meant “to intimidate Tatars not loyal to the current administration in Crimea.”