I agree with Fincher 100% in principle, but he did knowingly break a federal law, no matter what the Silver Bullet says. This is the same baiting tactic used by the Imams on a plane, and not very wise, IMHO.
So I went off to read the Silver Bullet - downloading as I write - and found this...
"I'm sure there will be no shortage of forum chat room warriors pompously declaring that Fincher is getting what he asked for by flouting the law in the local media. They will be wrong, and as shallow in their opinions as they are in their commitment to liberty."
Either we are equal or we are not. Good people ought to be armed where they will, with wits and guns. Merry Christmas NRA KMA
The only way you get to challenge it in court is to be charged with violating it.
You need a real case or controversy, plus some actual (or immediately potential) harm that can be fixed by a court in order to have standing. Fincher couldn't just challenge the NFA on a theoretical basis - otherwise so could all of us, and the courts would be dealing with millions of cases per month.