Any party with a candidate on the national ballot should be automatically included in the national debates. They may indeed be the game changers and the public has a right to hear them right along side those older, more funded campaigners. We are a nation of public freedoms and political parties fall under those freedoms.
If these fringe parties were relevant, popular opinion and media preference alone would naturally include them in the debate rotation. However, they are not. All outside parties have the burden of proof of showing that they are relevant and meaningful e enough to warrant inclusion. This prevents excessive and silly inclusion of fad and special interest parties in the debates.
Because of so many parties existing in the United States, if the Libertarians and the Greens had the right to be in the debates, then so can the remaining 212 active political parties. Conditions need to be met: Garner 15% of the national vote, and that party will be allowed to participate in the debates, not because the party is incorrect or irrelevant, but simply because time is not a luxury the US can afford due to so many parties existing.
No, no lawsuit should be necessary for the Libertarian and Green Party candidates to participate in the national debates. Both parties are well-known and deserve a voice in the debates. The two-party system is obsolete in the country, and the public is tired of feeling as if they have no real choice.
No, the Libertarian and Green parties should not have to sue the Debate Commission to be included in national debates, because they should already be invited to participate. Parties outside of the Republican and Democratic parties have a hard time getting noticed because they are not included, however, they shouldn't have to sue the Debate Commission.