WASHINGTON (AP) — A federal appeals court on Tuesday upheld a retired New York Police Department officer's conviction and 10-year prison sentence for assaulting a police officer during the Jan. 6, 2021, siege at the U.S. Capitol.

A three-judge panel from the U.S. Court of Appeals for the District of Columbia Circuit rejected Thomas Webster's claims that he was convicted by a biased jury.

Webster, a 20-year NYPD veteran, argued that the entire jury pool in Washington, D.C., was "presumptively prejudiced" against him. But the panel found no evidence that the jury pool had any preconceived notions about Webster, "or even knew who he was."

Jurors rejected Webster's claim that he was defending himself when he tackled Metropolitan Police Department officer Noah Rathbun and grabbed his gas mask. They convicted Webster of all six counts in his indictment, including a charge that he assaulted Rathbun with a dangerous weapon, a flagpole.

Webster drove to Washington from his home near Goshen, New York, to attend then-President Donald Trump's "Stop the Steal" rally near the White House on Jan. 6. Webster was wearing a bulletproof vest and carrying a Marine Corps flag on a metal pole when he joined the mob that stormed the Capitol.

Trump nominated two of the three judges who decided Webster's appeal.

The appellate court panel said Webster hadn't shown that the jury pool in Washington was "structurally incapable" of producing fair juries for Capitol riot defendants.

"Webster asserts that the District overwhelmingly voted for President (Joe) Biden and historically votes for Democratic candidates," the ruling says. "That may be. But the political inclinations of a populace writ large say nothing about an individual's ability to serve impartially in adjudicating the criminal conduct of an individual."

Webster's 10-year prison sentence is one of the longest among hundreds of Capitol riot cases. He was the first Jan. 6 defendant to be tried on an assault charge and the first to present a self-defense argument.

Over 850 people have been sentenced for Capitol riot convictions. Only 10 of them have received a longer prison sentence than Webster, according to an Associated Press review of court records.

The panel rejected his argument that the length of his sentence was "substantively unreasonable" compared to other Capitol riot defendants.