The doctrine is an exception to the supremacy clause under the U.S. Constitution, which basically says that federal law over-rides state law. The state action doctrine perhaps should better be termed state action immunity, because it gives immunity against antitrust laws when the state has enacted laws allowing independent physicians to negotiate jointly under state supervision. If the state immunities are lacking supervision, then those laws could be challenged successfully. The immunity should be carefully defined as to what law is involved and what the immunity is intended to accomplish. Without the state law, you can only go to federal court and litigate federal claims.
Federal court is harder to get into and harder to stay in than state court, for the most part.
You'd be suing under federal law such as violation of the Sherman Act and the Clayton Act. The Campbell Bill was designed to give exemptions to physicians in price negotiations with managed care companies, for the most part. So it was not consistent with the other exemptions that are out there, which essentially go to businesses or industries as a whole. The exemption that the insurance industry has extends only to insureds. Insurance companies do not have an antitrust exemption in dealing with providers.