I've seen the term used quite a bit, but it seems to me that the term, "constitutional carry" is a malapropism. Maybe someone can explain it in a way that a simple guy like me can understand, but if a right is constitutionally guaranteed, what is the point of a statute--a subordinate law--declaring that the right is guaranteed?
It's not a malapropism, although the term "constitutional carry" can be confusing.
Strictly speaking, "constitutional carry" refers to the U.S. Second Amendment. When a state adopts constitutional carry, it declares we, the people, can keep and bear arms in accordance with the Second Amendment.
Should that be necessary? No, of course not; most unfortunately, however, the Second Amendment isn't the law of the land in practice. Any time a state deliberately affirms the Second Amendment, it takes a step forward.
Most, but not all states have bills of rights embedded in their constitutions. California, for example, had language to guarantee the right of the people to keep and bear arms, but removed it during the (I believe) 1970s. The language varies considerably from state to state. Wisconsin has a provision in its constitution to guarantee the right to keep and bear arms, but has passed numerous laws to infringe it. Some of those laws have been declared illegal by courts in that state; most unfortunately, some of those that have been declared illegal are still being enforced by some police departments.
The simple—and logical and sane—solution would be for the Wisconsin legislature to declare full support for the U.S. Second Amendment. Very few politicians have the moral courage to do so. We'll see what happens.