Some states intend to “explore” ways to block those on terror watch lists from buying guns. Already, according to this story, the state of New Jersey blocks people on the list from purchasing guns, something which would seem to be unconstitutional. Consider the Second Amendment to the U.S. Constitution:
A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.
Owning a gun is a Constitutional right, not just a privilege, like driving a car. In addition, the Constitution requires “due process”, which is not something that occurs when someone is added to terror watch lists by anonymous bureaucrats.