If the lawsuit worked, this stage would be more crowded. (AP Photo/Jeff Roberson, File)

The Libertarian Party and Green Party and their 2012 candidates for president are readying a legal complaint against the Commission on Presidential Debates, hoping that a new legal argument -- an anti-trust argument -- will break the "duopoly" that's dominated the stage.

The legal complaint, which was sent early to The Washington Post, argues that a "cognizable political campaign market" is being corrupted by the commission's rules. The commission, a private entity set up after the League of Women Voters' 1992 debates allowed third party candidate Ross Perot to participate, has withstood yearly assaults from the likes of Ralph Nader, Pat Buchanan, and former Congressman Bob Barr. None of them have gotten past a 1999 commission rule: No candidate gets onstage unless he or she is polling at 15 percent or better.

Bruce Fein, the attorney for the new plaintiffs, argues over 43 pages that keeping them out of a "multi-billion dollar" market violates "antitrust laws, the First Amendment, and District of Columbia tort law."

"The unlawful agreement among Defendants has several illicit purposes," writes Fein. "The first is to acquire, maintain, and exercise duopoly control of the multi-million dollar market in organizing, promoting, sponsoring, and fundraising for holding national general election presidential and vice-presidential debates to artificially advantage the Democratic and Republican Party candidates... the second illicit purpose is to acquire, maintain, and exercise duopoly control over, and to exclude and severely undermine competition in, the multi-billion dollar market of organizing, promoting, fundraising for, and engaging in general presidential and vice-presidential election campaigns."

In an interview, Fein called the new complaint "pioneering," and credited the insight to failed 2012 independent candidate Rocky Anderson.

"He asked me fly out to Salt Lake City and visit and discuss this issue, which I did," said Fein. (Anderson was that city's mayor. "How about an anti-trust suit? People didn’t take it seriously at time, but I thought about it and discussed it with Gary Johnson and Jill Stein, the plaintiffs here. The difference between this case and other cases is our theory of relief and complaints."

Johnson and Stein, respectively, were the Libertarian and Green Party nominees for president in 2012. Both are likely to run again in 2016. When the complaint is filed in the District of Columbia next week -- the precise date is pending -- Fein and his plaintiffs will join a crowd of people asking for lower debate thresholds. In March, with some fanfare, a few dozen old political hands launched a group called Change the Rule, asking for no real change to the commission beyond the softening of the 15 percent rule.

Fein's group is going further, asking a court to rule that "the fifteen percent criterion used by Defendants continues to violate the First Amendment" and for "an order compelling the dissolution of the Commission and an injunction against any further boycott or other agreement in restraint of trade between the RNC and the DNC or any of their candidates or their agents."