Enforcement of the Federal Gun Free School Zone law in California.
Well, let's see, over in Arizona the "federal" government is objecting to Arizona enforcing federal law, and they've even filed a lawsuit to prevent the enforcement. So, who would enforce the federal GFSZ law in California?
"Enforcing" is a broad term.
In 1991, the California Supreme Court declared that there is no such thing as a crime against an individual, there are only crimes against the state. I mention this for the benefit of any legal historians who might happen across this thread. This decision precludes any private criminal prosecution.
I do not know of any mechanism by which a private person may pursue a Federal, private criminal prosecution. This leaves state, local and Federal law enforcement agents with the authority to make an arrest for violation of a Federal statute.
Citizen's arrest in the "sue me" state for violations of California law are problematic at best. For Federal crimes, it is theoretically possible but highly unlikely.
Prosecution for violation of the Federal statute can only take place in a Federal Court after one has been indicted by a Federal grand jury. Contrary to what one sees on television, an FBI agent can not make an arrest without first obtaining an indictment.
With rare exceptions, such as an arrest to prevent the commission of a Federal crime, Federal law enforcement officers are prevented from enforcing state or local law.
In recent years, local law enforcement agencies have created joint state and federal task forces to target certain criminals. I would hope that they are mindful of their respective roles and limitations.
California has a statute permitting Federal law enforcement to make arrests for violating state crimes. I've not run across an appellate decision upholding that statute but its legality is dubious, combined with the DOJ directive instructing FBI agents who have been deputized as Federal Marshals; it is highly unlikely for circumstances to arise for an arrest to be made under the California statute.
I have not read the court documents on the Arizona immigration law that was recently passed and so I can not comment on anything specific to the case other than to say, long before we had modern police forces, local law enforcement has always had the authority to make an arrest for violation of Federal statutes.
Personally, I don't see the current US Supreme Court changing that.
I have read the law that was passed, its provision that everything in it should be interpreted to comply with Federal law makes it unlikely that any section will eventually be overturned, if there is an ambiguity, the Courts are free to interpret the ambiguity in favor of Federal law.