A technical requirement that Pennsylvania voters write accurate dates on the exterior envelope of mail-in ballots was again the subject of a court proceeding on Thursday as advocates argued the mandate unfairly leads to otherwise valid votes being thrown out.

A five-judge Commonwealth Court panel heard about two hours of argument in a case that was filed in May, even though the date requirement has been upheld both by the state Supreme Court and the U.S. Court of Appeals for the Third Circuit.