SALT LAKE CITY — The ACLU of Utah is set Tuesday to announce a lawsuit against the state over the decision not to recognize marriages of same-sex couples performed before a stay was issued in the Amendment 3 case.

The civil liberties organization started looking for plaintiffs on Jan. 8, the same day Gov. Gary Herbert's office issued a directive putting state recognition of gay and lesbian newlyweds "on hold," based on counsel from Attorney General Sean Reyes.

The U.S. Supreme Court had issued a stay two days earlier of U.S. District Judge Robert Shelby's Dec. 20 ruling that struck down Utah's voter-approved constitutional amendment defining marriage as between one man and one woman.

Reyes said his office was not making a determination of the validity of more than 1,000 marriages performed between the ruling and the stay but concluded the language of Amendment 3 did not allow state recognition of the marriages.

On Thursday, the Utah State Tax Commission said same-sex couples married in Utah or any other state before Dec. 31 are able to file their 2013 returns as married.

— Lisa Riley Roche

Email: lisa@deseretnews.com, Twitter: DNewsPolitics