David Friedman Thinks that Municipalities "Boycotting" Arizona Might Just Be Unconstitutional

An interesting thought. The grounds? Any of the following:
The Citizens of each State shall be entitled to all Privileges and Immunities of Citizens in the several States.
No Tax or Duty shall be laid on Articles exported from any State.
No Preference shall be given by any Regulation of Commerce or Revenue to the Ports of one State over those of another: nor shall Vessels bound to, or from, one State, be obliged to enter, clear, or pay Duties in another.