It IS true. The U.S. Supreme Court could have taken the case and ruled that the tax stamp was constitutional. Could they not have?
In that case, Mr. Miller was guilty whether or not he was a Militia member. If Mr. Miller had purchased the stamp, he could have avoided the whole mess, could he not have? Did Mr. Miller have to be a Militia member to purchase a stamp? No.
Do you not understand the case and what law Mr. Miller violated? Did you think he was arrested for carrying a weapon that was only allowed for Militia meembers? Did you think he was arrested for carrying an illegal weapon?
Sure they could have. Instead they remanded with instructions go decide the case on the basis of the nature of the weapon alone. If Miller's possession of the weapon is protected, then he goes free. If not, Miller can be convicted.
The reason he would go free, would be that charging him with a crime for failing to pay a tax on his weapon would have violated HIS Constitutional right to keep and bear arms.
Thus, the effect of the Miller decision was that NFA 34 was Constitutional for some arms and unConstitutional for others, regardless of the militia membership of the person being charged.