[wolfordstudent]

The relationship between a CRNA and a surgeon is purely collaboration. A CRNA that takes orders from a surgeon will end up making a mistake eventually.
E.g., If the patient has a vagal response d/t to surgeon's maneuvering in the patient's abdomen, you as a CRNA will tell the surgeon to stop - and any smart surgeon WILL stop, until the patient is stable.

As for the legality of the issue, even if an MDA supervises a CRNA, if something goes wrong, in a court of law, a CRNA cannot use the excuse: " I did ... that because the MDA told me to". In a court of law you are all by yourself, because you are supposed to make independent decisions.
If you are a CRNA uncomfortable with the medical direction during a case, you can sign out. Period.

All this legal knowhow comes from three MDA's I work with who have been sued.