The constitution requires that a president BE certain things, but it doesn’t specify a procedure for proving those things, or establish penalties, or anything else.
Except, that it also establishes the procedure for electing the president, with roles for electors and the congress. So we can assume it is their job to make sure someone is eligible before electing them. But to do so, there’s no requirement that a candidate produce a birth certificate, or any other particular proof. If the electors and the congress decide the person is eligible, then that decision is all that’s needed.
To have a hope of a legal case, beyond the issues of standing, the birthers needed to cough up some proof that the facts really are contrary to the constitutional requirements. Not that they suspect it. Not that they aren’t satisfied. Proof that as a matter of *fact*, Obama was born somewhere else. Then it might be concievable that a court could hear and rule on the eligibility question.
The official “Declaration of Candidacy” that the candidate signs has to be verified. We aren’t suppose to just take the word of the candidate. Maybe the real defandants should be all of the secretary of states. :)
If the Constitution does not specify, then it falls to the people and the states.