Harvard Law professor David Barron is a former acting assistant attorney general in the Obama administration. While in President Obama’s Office of Legal Counsel he wrote memos justifying the extrajudicial killing of an American citizen abroad. Last year, the president nominated Barron to a seat on the U.S. Court of Appeals for the First Circuit and a vote on his nomination is expected this week. I am going to fight this nomination, because I believe Barron has disqualified himself from serving as a federal judge. I’ve read the Barron memos concerning the legal justification for killing an American citizen overseas...