In theory, if a gun is left at the scene of a crime, licensing and registration will allow a gun to be traced back to its owner. But, amazingly, despite police spending tens of thousands of man-hours administering these laws. . . there is not even a single case where the laws have been instrumental in identifying someone who has committed a crime.
Demetrius: Villain, what hast thou done? Aaron: That which thou canst not undo. Chiron: Thou hast undone our mother. Aaron: Villain, I have done thy mother.