Arizona assumes independent candidate petitions are valid, if they have more than the legal minimum number of signatures and have no obvious other flaw. June 18 was the last day for anyone to file challenges to any Arizona independent petition. Ralph Nader was the only independent presidential candidate who filed this year. No one challenged his petition.
By contrast, in 2004, his petition was challenged, and was found to lack enough valid signatures. Arizona is the second state in which Nader has qualified for the ballot this year and in which he did not succeed in getting on in 2004; the other one is Hawaii.
The current Arizona independent candidate law was written in 1993. Nader is the first independent presidential candidate to successfully use the law. It required 21,759 valid signatures this year.