Lawyers for Texas argue the state has an interest in procreation and opposite-sex unions are the only relationships that can produce the offspring needed for economic growth.
Some of those watching the match booed Mack Beggs when he easily defeated his female opponent to win the state championship.
The Texas branch of the American Civil Liberties Union has invested in a transgender rights Facebook campaign that is summed up as, "Taking A Seat, Making A Stand."
Lady Gaga, Ariana Grande, and more than 100 others have signed an open letter urging Texas lawmakers to reject anti-LGBT legislation.
Jess Herbst, the state's first transgender state official, led her first town council meeting Tuesday as her authentic self, and says she's been well-received in her conservative Texas town.
Turnout surpassed 40,000 people in the Texas capital, according to police estimates.
The case could chip away at the rights won with marriage equality.