It’s nice to see someone in these discussions who actually knows how the software works. First of all, the Illustrator file doesn’t actually have “layers,” it has “groups” on a single layer. If the document was forged the way people claim, it would have actual layers.
Second, nobody would use Illustrator for a job like this. If you’re going to copy and past fragments of other documents to create a forgery, you’d use Photoshop, a program a lot more people have heard of. I wonder how many of the conspiracy theorists even know Adobe made a product named Illustrator before all this.
Third, even the internal details of how the forgery “must” have been created don’t make sense. We’re supposed to believe that they copied one numeral ‘1’ from one source and a different numeral ‘1’ from another—what the heck for? If you’re bad enough at this that you wouldn’t even flatten the image, why wouldn’t you just duplicate the ‘1’?
And fourth, one thing I agree with the birthers on is that an online PDF of a birth certificate isn’t legal proof. But if you can’t verify the veracity of a digital document, you can’t prove it a forgery either.
It doesn’t have to be Illustrator — there are lots of image processing apps that use layers to edit documents, and the layers stay if you are stupid/lazy enough to forget to flatten it before publishing it.