What it means depends on the nature of the ruling, of course... We COULD lose, you know! But assuming we win, Emerson wouldn't immediately result in any law except the one Emerson violated being struck down.
It would, however, put us in a very strong position to challenge other gun control laws on the same basis. You'd still, unfortunately, have to violate it, and get prosecuted, and take the chance of going to jail and becoming a felon, in order to challenge them. This country DESPERATELY needs a way to challenge the constitutionality of laws without risking prison time and the loss of civil liberties!
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Sic semper tyrannis!