Sixty-three Texas legislators have filed an amicus brief calling on a federal appeals court to uphold Texas' ban on gay marriage.

U.S. District Judge Orlando Garcia struck down Texas' ban in February, saying it demeans the dignity of gay couples for no legitimate reason. The state appealed the case to the Fifth Circuit Court of Appeals in New Orleans, which has yet to schedule oral arguments.

The Legislature's Texas Conservative Coalition (TCC) filed its friend-of-the-court brief on Monday, arguing that allowing gay couples to marry may open the door to other unions, including plural marriages and incest.

“Another ground cited by supporters of Texas's marriage laws and subsequently dismissed by the district court is that recognition of same-sex marriage 'could lead to the recognition of bigamy, incest, pedophilia and group marriage,'” the document states. “As already discussed in this brief, restrictions on marriage relating to these moral considerations remain valid. Thus, the goal of actively trying to prevent those practices from becoming valid is entirely rational public policy.”

(Related: Texas' gay marriage ban is not discriminatory; it treats all couples the same, AG argues.)