Re: Opinion from Cockytalk legal dept, please
I'm no attorney, but if a state law has a requirement of showing ID upon request by an authority, you have to show the ID. Later, you could challenge the law as unconstitutional in federal courts, I assume.
As far as resisting arrest, you can't resist arrest until you're under arrest. Whether or not the officer's grabbing of her arm constituted arrest will be up for debate in court probably. Likely, with the subjective factors (such as running, headphones, not seeing the cop), the court will probably rule she was not under arrest and, therefore, could not be resisting.
RULE OF THUMB: It doesn't matter if you don't like the cops, you have to abide by the law. Later (or prior to arrest, provided an injury to you or your interest is imminent) you can challenge the law and the conviction/charge.
Again, I'm no attorney or law-educated person, but this seems like a situation where the charges will be dropped and the arrestee may later (a) challenge the statute/ordinance requiring the providing of ID and (b) bring suit for her injuries resulting from the arrest.