Although I like the result this case is ridiculous. The state can grant monopolies? That’s at least better than letting the feds do so.
I totally agree with you....
The Sherman Antitrust Act (1898) banned monopolies. In 1943, the Supreme Court carved out a "state action" exception-- if a state, by law, did something like banning anyone not licensed in the state from practicing law or medicine, that would not be seen as a violation of the Sherman Act, on the theory that Congress didn't intend to stop states from exercising their traditional regulatory powers.
In this case, the state of Alabama went a step further-- they first limited the practice of dentistry to licensed dentists (OK so far), and they then delegated to the state's dentists the power to decide what "the practice of dentistry" means. The dentists, predictably, started banning non-dentists from doing routine things like teeth-whitening. The Supreme Court held that the 1943 exemption applies only to monopolies created directly by the state's elected officials, and the state cannot delegate to people who compete in the marketplace the power to exclude their own competition.