The headwind against Pennsylvania’s ban on same-sex marriage, which began with the U.S. Supreme Court’s June decision striking down DOMA’s restriction of marriage to one man and one woman, gathered force Thursday as a suit was filed in Philadelphia challenging as unconstitutional DOMA’s permission for states to disregard same-sex unions made in other states.

It’s the second federal suit to be brought in addition to two pending state cases over the same-sex marriage issue in Pennsylvania.