AUSTIN – Texas’ reasons for upholding its gay marriage ban defy both logic and the trend set by several recent federal court rulings, lawyers acting on behalf of two same-sex couples argued in new briefs filed Tuesday.

In the 61-page brief, San Antonio-based lawyer Daniel McNeel Lane wrote the issue facing the federal appeals court was “a simple question of equality and fairness.”

U.S. District Judge Orlando Garcia, a Bill Clinton appointee based in San Antonio, ruled the ban unconstitutional in February because it violated gay couples’ 14th Amendment rights to due process and equal protection.

Acting as the state’s counsel, Attorney General Greg Abbott appealed, arguing the issue of gay marriage should be left to the voters and state lawmakers rather than courts, it relied most heavily on the argument that Texas has a “legitimate state interest” in encouraging opposite-sex couples to procreate.

“Even accepting procreation as a legitimate state interest, it defies logic and the undisputed evidence to claim that preventing lesbians and gay men from marrying will encourage heterosexual marriage or, conversely, that allowing lesbians and gay men to marry will discourage heterosexual marriage,” Lane challenged in the brief.

“Nor do principles of federalism support the State’s appeal. It is axiomatic that courts will not sit idle when the actions of a majority jeopardize the constitutional rights of minorities, particularly groups subject to historical disfavor, such as gays and lesbians.”

Lane added the state’s argument contradicts 22 federal court rulings that have recently struck down gay marriage bans in other states. The brief frequently cites 7th Circuit Court of Appeals Judge Richard Posner’s recent ruling, striking down the Indiana ban on same-sex marriage.

“Indiana’s government thinks that straight couples tend to be sexually irresponsible, producing unwanted children by the carload, and so must be pressured (in the form of governmental encouragement of marriage through a combination of sticks and carrots) to marry, but that gay couples, unable as they are to produce children wanted or unwanted, are model parents—model citizens really—so have no need for marriage. Heterosexuals get drunk and pregnant, producing unwanted children; their reward is to be allowed to marry,” wrote Posner.

“Homosexual couples do not produce unwanted children; their reward is to be denied the right to marry. Go figure.”

In total, four federal appeals courts have overturned state gay marriage bans. The Ninth Circuit Court of Appeals in San Francisco is hearing oral arguments in a same-sex marriage case this week.

The fight for gay marriage has netted one major loss, however, when a federal judge in Louisiana upheld the state’s ban last week.

Reached for comment Tuesday, Chasnoff said the Louisiana argument is a weak one: “If you look at the Louisiana decision, basically what the court there says is that if something is approved in a democratic process then that should be what prevails. Well, then there’s no need for a Constitution and Constitutional protections. The essence of a Constitution is that it protects minority view from majority tyranny.”

The Texas case is now pending in the 5th U.S. Circuit Court of Appeals. The New Orleans court is widely considered one of the nation’s most conservative, making it the most likely source of such a split.

Gay marriage advocates have said any outcome in appeals court would be a win for the movement. If it upholds Judge Garcia’s ruling overturning the ban, it will bolster LGBT activists’ case. If it becomes the first appeals court to toss out such a ruling, creating a circuit court split, it could put the Texas case on a fast-track to the U.S. Supreme Court.

The state has until Sept. 26 to file a response to Tuesday’s brief. The appeals court will then set a date for oral arguments.

“I just hope we have the opportunity to argue this and have an opinion out by the end of the year,” said Chasnoff. “But that may be optimistic.”

The plaintiffs in the case are Mark Phariss and Victor Holmes, two Plano men who wish to marry here, and Cleopatra De Leon and Nicole Dimetman of Austin, who are legally married in the state of Massachusetts and want Texas to recognize that marriage. Holmes and De Leon are both Air Force veterans.

Lauren McGaughy is a reporter in the Houston Chronicle’s Austin bureau. She can be reached at lauren.mcgaughy@chron.com or on Twitter @lmcgaughy.