Federal court decision:
"A state cannot impose a license, tax or fee on a constitutionally protected right."
Murdock vs.Pennsylvania 319 US 105 (1942)

For those who rely on law and common sense, the possession of firearms is clearly "a constitutionally protected right". Regardless of this truth, most states require a citizen to pay a "fee" (registration or background check "fee") in order to obtain a "license" (concealed carry "license") before keeping and/or bearing a firearm. And, a federal and/or state "tax" (firearms and ammunitions sales "tax" or machine gun "tax" collected by the BATF) is always levied at the time of firearm transaction.

Criminals can not be compelled to register guns. The U. S. Supreme Court determined,
"...that a felon who has a gun cannot be compelled to complete such forms, because it violates the Fifth Amendment right against self incrimination. That's right, registration -- not in your case of course but in the case of a criminal -- is a self-indictment of a crime, and is therefore prohibited."
Haynes vs United States (1968).

In 1856, the U. S. Supreme Court ruled,
"Local law enforcement has no duty to protect individuals but only a general duty to enforce the laws."
South vs. Maryland, 59 US (HOW) 396, 15 L. Ed. 433 (1856).

A U. S. Federal Appeals Court declared in 1982,
"There is no constitutional right to be protected by the state against being murdered by criminals or madmen."
Bowers vs. devot, U. S. Court of Appeals, 7th Circuit 686 F. 2d 616 (1982).

The U.S. Supreme Court declared,
"The Constitution does not impose a duty on the state and local governments to protect citizens from criminal harm."
DeShaney v. Winnebago County Department of Social Services, 489 U.S. 189, 109 S. Ct. 998, 103 L. Ed. 2d 249 (1989)

"The purpose of the Second Amendment is to restrain the federal government from regulating the possession of arms where such regulation would interfere with the preservation or efficiency of the militia."
U.S. v. Hale, 978 F.2d 1016 (8th Cir.1992)