Groups Challenge Same-Sex Marriage in Mass.

Conservative groups filed a motion in federal court Monday seeking to block the legalization of gay marriage (search) next week, arguing that the state's highest court violated the U.S. Constitution with its landmark November ruling.

After unsuccessful attempts to overturn the case in state court, this marks the first time the Massachusetts gay marriage case has been brought into federal court.

The motion argues that the court usurped the constitutional powers of the Legislature and the governor when it changed the state's marriage laws. This, in turn, violated the U.S. Constitution, which guarantees a uniform separation of power in all of the states, the motion argues.

Liberty Counsel, a Florida-based nonprofit organization, and several other conservative groups filed the case on behalf of Robert Largess of Boston, vice president of the Catholic Action League (search).

A similar motion in state court, filed by 13 state lawmakers, was rejected by the Supreme Judicial Court last week.

Mat Staver, president and general counsel of Liberty Counsel, issued a statement Monday saying "the federal courts are obligated to step in to ensure that Massachusetts is following the basic principle of separation of powers that is vital to our very system of law and government."

Legal expert Shari Levitan, an attorney with Holland & Knight of Boston, called the latest motion a "Hail Mary pass."

"When the laws that are made violate the state Constitution, it is the court's purview to say yes or no," Levitan said. "I think the significance of this is not the case itself but that it highlights such strong emotions. People are willing to go to the mat with any argument to push their claim."