A Department of Defense spokeswoman said it is aware of the lawsuit and is reviewing the filings.
The army said in a statement that it concluded the soldier’s operation can be considered a reason for discharge.
A federal judge on Wednesday ordered the Pentagon to turn over thousands of documents.
The legislation still needs to be reconciled with the Senate's version of the national defense bill.
Army Gen. Mark Milley said that readiness has not been compromised by transgender individuals serving in the military.
At least 100 people at a National Pride Month event Monday at the Elkhorn Conference Center on Fort Carson.
The House passed, by a 243-183 vote, an amendment to block Trump's transgender ban from remaining in effect.
Deirdre Hendrick and Alice Ashton both faced challenges as transgender women in the military.
Map Pesqueira, a transgender University of Texas student, was to receive a scholarship, but policy changes may change that.
The academies that educate officers for the armed forces have begun to implement the administration's transgender ban.