Atheist lawyer Michael Newdow, who has unsuccessfully challenged religious trappings of presidential inaugurations past, took his latest dispute — this one involving Barack Obama’s inauguration — to the U.S. Court of Appeals for the D.C. Circuit Tuesday.

A little background: Last December, Newdow and his fellow plaintiffs sued the Presidential Inaugural Committee and Chief Justice John Roberts Jr., among others, in an effort to block Roberts from feeding then President-elect Obama the line “so help me God” at the end of the oath of office and Obama from repeating it. The plaintiffs say the phrase violates the establishment clause of the First Amendment.