Here is the short decision of the Oklahoma State Supreme Court in Lawhorn v Ziriax, 2012 OK 78. The decision implies, but not does explicitly say, that qualified parties in Oklahoma cannot nominate presidential electors unless their party holds a national convention. This is based on an incidental part of the election law that says presidential elector candidates must take an oath to support the candidate chosen at that party’s national convention. The irony of this interpretation is that even if Americans Elect had gone ahead with its original plans, it never planned to nominate a presidential or vice-presidential candidate at a national convention. Instead, the party expected to nominate via an on-line vote of any registered voter in the nation who wished to participate.
The decision also mentions that the national Americans Elect rules do not authorize any state party organizations, which implicitly seems to say that the national rules of the Americans Elect Party take precedence over Oklahoma state election laws, which give state parties the authority to choose presidential elector candidates. Yet in 2000, the last year the Libertarian Party was a qualified party in Oklahoma, the Libertarians passed a bylaw saying all registered voters could vote in the Oklahoma Libertarian primary. The party said it had a First Amendment Freedom of Association right to decide for itself how to run its nomination process.