Consider first the practical implications. Hannity’s specific pitch calls for retired law enforcement and members of the military to donate 15 hours of guard time per week, in exchange for which they are excused from paying all income taxes, state and federal. He proposed this structure because it makes the program “free,” which it would have to be to make it feasible on such an enormous scale. (In reality, the money participants would save on federal income tax is probably more than what they’d make if they were simply paid by the federal government for their time.)

But that also means these guards are volunteers. To whom are they accountable? What use of force rules govern their behavior? Are they subject to the loose legal standard the Supreme Court has applied to police, which says mere “reasonable” belief in the presence of a threat justifies the use of deadly force? What happens when one of these guards makes a mistake? Are they prosecuted like the private citizens they are or accorded the protections and benefit of the doubt law enforcement consistently receive?

And mistakes would happen. Hannity’s retirees would be more likely to make mistakes than active duty military or police, as with age comes decline in eyesight, hand-eye coordination, reaction time, and other aspects of physical fitness that are useful when you’re standing around with a gun, looking for threats to shoot.