off duty police officers should not carry because they "might be needed" they should carry for protection. a cop is more likely to be assaulted because any given cop likely has jailed at least one violent criminal who is now out and might take a chance at revenge.
of course, cops should not have a different set of laws from teh general populace, and if a cop can be allowed to carry for protection, then every other citizen should be able to as well.
For every thug seeking revenge on a cop, there are probably 10 thugs who would rather victimize a civilian vs a cop.