The one-paragraph notice contained no argument but formally signals that Attorney General Greg Abbott intends to challenge the ruling by San Antonio-based Judge Orlando Garcia. On Wednesday, Garcia issued a preliminary injunction against the ban—only to suspend his own ruling to allow the state to appeal.
Two gay couples have challenged Texas' constitutional amendment and a longstanding law prohibiting same-sex marriage.
Garcia said states don't have the power to deny people the fundamental right to marry and enjoy its benefits.
His ruling added to a tangled web of decisions, state laws and legal opinions across the country that is expected to eventually end up before the U.S. Supreme Court. There are civil rights lawsuits in 24 states asking courts to overturn state gay marriage bans, and gay rights groups have won recent victories in other conservative states, including Utah and Oklahoma.
U.S. Attorney General Eric Holder said this week that state attorneys general were not obligated to defend local laws if they believed the laws violated the U.S. Constitution. Democratic attorneys general in at least six states have declined to defend same-sex marriage bans that have been challenged in court by gay couples.
That's not the case in Texas.
Abbott spokeswoman Lauren Bean said Thursday's notice was filed in district court, which will then send the case record to the 5th U.S. Court of Appeals in New Orleans.
She added, "The next thing we'll file will be our brief in the 5th Circuit, which won't happen for another month or two."
Abbott is the leading candidate to replace Republican Gov. Rick Perry but has taken a conciliatory tone after Garcia's ruling. He said Wednesday that "there are good, well-meaning people on both sides" of the same-sex marriage debate, while also insisting that states have the right to set their own marriage laws.