Declaring that a Harvard University law professor nominated to the U.S. Court of Appeals violated the Bill of Rights by penning a memo justifying the administration's drone killing of Americans overseas, Sen. Rand Paul on Wednesday vowed to fight David Barron's appointment.

“I cannot and will not support a lifetime appointment of someone who believes it is okay to kill an American citizen not involved in combat without a trial,” Paul said in a Senate floor speech in opposing Barron's nomination to the Boston court, considered a sure bet.

“I rise today to say that there is no legal precedent for killing American citizens not directly involved in combat and that any nominee who rubber stamps and grants such power to a president is not worthy of being placed one step away from the Supreme Court,” said Paul. “It isn't about seeing the Barron memos. It is about what they say. I believe the Barron memos disrespect the Bill of Rights.”

Barron is a former Justice Department official who wrote at least one legal memo on the use of drones against Americans overseas, even those not attacking U.S. troops.

Paul said it is easy to dismiss the Barron memo because those targeted by drones are considered “evil.” He added: “These traitors are betraying a country that holds dear the precept that we are innocent until proven guilty. Aren’t we, in a way, betraying our country’s principles when we relinquish the right to a jury trial?”

He also said that Barron was promoting U.S. vigilantism. “Do we have the courage to denounce drone executions as nothing more than sophisticated vigilantism? How can it be anything but vigilantism? Due process can’t exist in secret,” he said.

News reports said that it was used to OK the drone killing of Anwar al-Awlaki, an American who linked to al Qaeda in Yemen.

A procedural vote on the nomination is expected today.

Paul's prepared floor remarks can be seen here.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.