Under the probation department rules, they were not permitted to speak, meet or e-mail during their five-year period of supervised release.
Before their arrests, Mangini and Roberts had lived together for 18 years, shared bank accounts, and helped raise a young girl.
"Defendants were in every way a family," Katz wrote in a 10-page opinion issued Tuesday. "The Due Process Clause [of the Constitution] protects highly personal relationships of deep attachment and commitment."
Katz, who had previously declined to consider the gay convicts' request on procedural grounds, issued his opinion a few weeks after the U.S. Court of Appeals for the Third Circuit directed him to address the issue on its merits.
"I'm elated," Mangini said yesterday in a statement issued by the American Civil Liberties Union, which represented the couple. "This opens possibilities. Finally we get to resume our lives together and dream for the future."
Catherine Roper, a staff attorney with the ACLU of Pennsylvania, said that "by honoring their commitment to each other and fighting to be together, Dan and Steven have helped to bring about groundbreaking law requiring equal treatment for same-sex couples."
Assistant U.S. Attorney Emily McKillip declined to comment.
Contact staff writer John Shiffman at 215-854-2658 or jshiffman@phillynews.com.