From the Judicial Watch press release:

Judicial Watch, the public interest group that investigates and prosecutes government corruption, announced today that it filed a Freedom of Information Act (FOIA) lawsuit on April 29 against the Obama Department of Justice (DOJ)to obtain records related to the DOJ’s decision not to defend the constitutionality of the Defense of Marriage Act (DOMA).

... The Office of Information Policy and the Referral Unit both acknowledged receipt of Judicial Watch’s FOIA requests but have failed to respond to these requests within statutory allotted time frame. In fact, the DOJ has failed to release any records or indicate when a response is forthcoming, prompting Judicial Watch’s lawsuit.

Also, Judicial Watch is getting more involved in the Prop 8 litigation:

On May 2, 2011, Judicial Watch separately filed an amicus curiae brief with the Supreme Court for the State of California supporting the right of California citizens to defend Proposition 8 when elected officials fail to do so. Proposition 8 states that "only marriage between a man and a woman is valid or recognized in California" (Case No. S189476).