The motion is to be filed Wednesday in advance of an Aug. 15 hearing on the matter.
The state government's reply is due Aug. 2.
The Supreme Court last week invalidated parts of a law that blocked the federal government from recognizing same-sex unions.
Seven gay couples in New Jersey have already sued, saying that the state's civil unions do not fulfill a state Supreme
Court requirement that gay couples receive equal treatment to what married couples get.
Now, the couples' lawyers are arguing that the state is blocking them from getting federal benefits.