The single best work was already cited by Col. Mustard:
http://www.shadeslanding.com/firearm...rotection.html
Kasler (RIP) was a lawyer, and a damned good one.
There's been one more recent case in California, where the Calif Supreme Court ruled that court bailiffs do not have a duty to protect people inside courtrooms, despite disarming them yet failing to disarm a murderous assailant.