Here are some Cal. Penal Code sections extending criminal liability to out of state persons in certain instances:
27. (a) The following persons are liable to punishment under the laws of this state:
(1) All persons who commit, in whole or in part, any crime within this state.
...
(3) All who, being without this state, cause or aid, advise or encourage, another person to commit a crime within this state, and
are afterwards found therein.
....
778b. Every person who, being out of this state, causes, aids, advises, or encourages any person to commit a crime within this state, and is afterwards found within this state, is punishable in the same manner as if he had been within this state when he caused, aided, advised, or encouraged the commission of such crime.
Not much case law that I found on these statutes, but they don't look good for the out-of-state mag shipper.
Ed