Gun Free Zone Liability Act

Via Insty comes this:

"If you create a gun-free zone, you're liable for any harm it causes."

On the surface, it sounds good, but is it? Who should it apply to? State and Federal governments? Private businesses?

I mean, it's a known fact that the police do not have a duty to protect you already. How could this be applied in reference to that?

Common sense, or nannyism?

UPDATE: Robb asks How about the opposite tack?

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