Felons cannot register guns because they cannot posses them. GCA 68 made it so. A felon in possession has no defense (since I am a felon, registering would be self-incriminating etc), since GCA 68 made it illegal period for a felon to possess arms and or ammunition.
The right to not talk (self incriminate) is still protected, but the action of buying/possessing is made an illegal act.
I think we are dancing on the head of a pin here.
Best.
We are not in disagreement. The issue was only registration of guns and admitting under oath to committing a crime on an official form. As it stands right now firearm registration laws only apply to the law abiding and not to the felons that the gun registration laws were presented as preventing from purchasing firearms.
With respect to the original topic. The same argument applies. They cannot compel a person to admit to a crime - illegal use of drugs - on a form.