You are right. The only way to prosecute him for perjury is to prove his is a fake and he knew it. The only way to do that is for Obama to produce his real, certified Hawaiian, long-form birth certificate, and that he’ll never do.
ex animo
davidfarrar
Or produce other examples of Kenyan birth certificates from the same period showing the difference. Or affidavits from the Kenyan authorities stating it's a fake. Or have it examined by experts who can attest that it's fraudulent. There are any number of ways that they can blow this document clear out of the water and not involve Obama at all.