From the Catholic News Service:

The U.S. bishops' Office of General Counsel said the Obama administration's decision to no longer support the Defense of Marriage Act in legal challenges ahead "represents an abdication" of its "constitutional obligation to ensure that laws of the United States are faithfully executed."

"Marriage has been understood for millennia and across cultures as the union of one man and one woman," the office said in a statement issued Feb. 23 after President Barack Obama instructed the Justice Department to stop defending the federal law passed by Congress and signed into law in 1996 by President Bill Clinton. [source]

Brian Brown is quoted later in the article as well.