Bono, a Federal law mandating concealed carry reciprocity would be just as constitutional as for example a Federal law mandating that marriage reciprocity (i.e. States could be forced to recognize gay marriages). Neither proposed law would be constitutional though, as they both contravene the 10th Amendment.
It would be constitutional under the full faith and credit clause. The proposed law would respect the public policy exception, since the two states that do not allow concealed carry would still not be required to recognize any permits.
No, it would make a mockery of the public policy exception.
In that case a Massachusetts employee of a Massachusetts company with a California subsidiary was injured while temporarily at the California subsidiary. Both California and Massachusetts had workman's compensation laws, and the employee was entitled to file a lawsuit under California law, but not under Massachusetts law. (Massachusetts law at the time allowed employment contracts to require the use of binding arbitration for such claims, California law explicitly banned employment contracts from having binding arbitration.) The court held 8-0 that California was not required to use Massachusetts' law to determine whether the employee could file suit in a California court of law.
Similarly, a state may not be required to use the law of another state to determine if a person may carry a concealed weapon, nor may it be required to accept the validity of marriages contracted in another state if such marriages could not be legally entered into in that state.
Federalism means that on these issues, as well as many others, each State decides for itself what shall be the proper policy in that State, without the interference of other States.
