A new round of litigation challenging President Donald Trump’s latest travel ban is underway in the Fourth and Ninth circuits, but another lawsuit in Washington, D.C., could pave an alternative legal road for the president’s opponents.

A federal judge in Washington, D.C., heard oral arguments on the now-expired March 6 travel ban executive order back in April but stayed the case after district courts in Maryland and Hawaii enjoined it and the U.S. Supreme Court got involved. The high court dismissed a challenge originating in Maryland as moot Tuesday, since the order expired last month.