Lawyers for police unions who want to upset New York City’s settlement of litigation over police stop-and-frisk practices ran into some tough questions Wednesday at the U.S. Court of Appeals for the Second Circuit.

Judges Barrington Parker (See Profile), John Walker (See Profile) and Jose Cabranes (See Profile) asked why police unions waited until Southern District Judge Shira Scheindlin (See Profile) found the police department liable for widespread constitutional violations and appointed a monitor to oversee reforms before trying to intervene in the lawsuit last year.