New Orleans' lawless superintendant of police, P. Edwin Compass, has declared, "No one is allowed to be armed. We're going to take all the guns."
The Compass order appears to be plainly illegal. Under section 1983 of the federal Civil Rights law, any government employee who assists in the illegal confiscation would appear to be personally liable to a civil lawsuit. Moreover, higher-ranking officials--such as the National Guard officers who have ordered their troops to participate in the confiscation--would seem to be proper subjects for impeachment or other removal from office (and attendant forfeiture of pensions), depending on the procedures of their particular state.
All police officers, National Guard troops, and U.S. Marshals take an oath to uphold the Constitution and the laws. It appears that carrying out an illegal order to confiscate lawfully-owned firearms from homes would be inconsistent with the oath, contrary to sworn duty, and perhaps a criminal act.
David Kopel at VC.