President Donald Trump’s ban on transgender military service has been the target of a growing number of lawsuits since he first announced the policy via tweet in late July. But now the controversial move has drawn the attention of the world’s highest-grossing law firm.

Latham & Watkins represents the LGBT civil rights group Equality California and several transgender members of the military in a federal lawsuit filed Tuesday in California challenging the constitutionality of Trump’s Aug. 25 directive to the heads of the military.