A Big Law attorney known for battling President Donald Trump’s proposed travel bans has joined Gov. Tom Wolf‘s efforts to defend Pennsylvania‘s recently re-drawn congressional districts before the U.S. Supreme Court.

Hogan Lovells partner Neal Katyal joined Wolf’s legal team last week, and on Monday he filed a response to calls from several Pennsylvania Republican lawmakers to have the U.S. Supreme Court upend a congressional map that the Pennsylvania Supreme Court drew up last month after determining that the previous map was unconstitutionally gerrymandered.