The bad news keeps piling up for the anti-gay National Organization for Marriage.

Just last week, a new CNN/Opinion Research Poll found that a slim majority of Americans actually support marriage equality for same-sex couples. A similar poll conducted by CBS and the Washington Post also found more Americans than ever before support marriage equality.

And, of course, we can't forget the former NOM strategist, Louis Marinelli, who jumped ship in early April and now supports marriage equality. We have a great interview with Marinelli here, by the way.

On the heels of the news that Atlanta-based King & Spalding would not represent the U.S. House of Representatives in the on-going legal battles against the Defense of Marriage Act, NOM announced today that it was launching an investigation into whether the law firm broke any rules of professional conduct or if the firm “acted illegally” in deciding to withdraw from the case.

“We will convene a panel of legal experts and ethicists to determine if any rules of professional conduct have been violated, or if the firm has acted illegally in reaching their decision,”Brian Brown, president of NOM, said today via the organization's blog. “We already know they have violated the moral imperative of acting in good faith and fair dealing. If our review concludes that the firm has violated any statutes or rules of professional conduct, we will initiate the appropriate disciplinary complaints.”

But Brown doesn't stop there.

“Representing clients who may be unpopular in some quarters is what lawyers do. The actions of King & Spalding would suggest that they believe an accused murderer is entitled to a vigorous defense, but the thousands-year old understanding of marriage is not, even though our marriage law was passed with overwhelming bi-partisan majorities and signed into law by President Clinton,” he added.

Don't think that shifting cultural attitudes toward same-sex marriage and wise decisions by private companies will do anything to deter NOM. They're committed to the fight just as much as equality advocates.

But just like with Marinelli, King & Spalding's decision not to defend DOMA is one small (albeit mostly symbolic) step toward victory and Brown's organization will continue to fight to deny those victories.