The motion, filed late Thursday, argued that the case of Arthur Smelt and Christopher Hammer does not address the right of gay couples to marry but rather questions whether their marriage must be recognized nationwide by states that have not approved gay marriage.

"This case does not call upon the Court to pass judgment ... on the legal or moral right of same-sex couples, such as plaintiffs here, to be married," the motion states. "Plaintiffs are married, and their challenge to the federal Defense of Marriage Act ("DOMA") poses a different set of questions."

It's a different case from a recent federal lawsuit by two unmarried gay couples in California who claim a civil right to marry under the U.S. Constitution.

The government said Smelt and Hammer seek a ruling on "whether by virtue of their marital status they are constitutionally entitled to acknowledgment of their union by states that do not recognize same-sex marriage, and whether they are similarly entitled to certain federal benefits.