One way criticize someone’s reasoning is by showing that if followed through it leads you to absurd conclusions. The occasional radical will simply bite the bullet and accept the absurd, often ridiculous, conclusion, but by and large people will change their reasoning, or just refuse to accept logic. Protectionists in the State of New Jersey have decided to eagerly bite the bullet.
A popular argument against protectionism is that if you follow the logic through, it implies you should have protectionism between states. Here is Russ Roberts laying it out:
If it’s true that theory and evidence in favor of protectionism are sufficiently strong to warrant economists abandoning their conclusion that free-trade policy is generally sound, then why shouldn’t economists… also start exploring the potential benefits of intra-national protectionism?  Surely a scholar not benighted with the free-trade “faith” ought to take seriously the possibility that, say, Tennesseeans could be made wealthier if their government in Nashville restricts their ability to trade with people in Kentucky, Texas, Rhode Island, and other states?
The usual protectionist defense rejects this absurd conclusion via some argument about differences in laws and institutions… or something like that. New Jersey’s protectionists, on the other hand, have decided to bite the bullet and are actually embracing the idea that interstate protectionism can make them better off. State legislators are trying to pass a law that mandates that all public servants must be New Jersey residents. The impacts would be far reaching:
The bill would affect teachers, firefighters, police officers, and all other employees of state, county, and local governments, as well as public authorities, boards, agencies, commissions, and state colleges and universities. Both full-time and part-time employees would be affected.
What’s great about this is that it really illustrates the flaws of protectionism that are often unintuitive when it occurs between nations. The tradeoffs you face are much clearer when the town you live in can’t hire the most qualified firefighters and teachers, and instead you’re left less qualified individuals who wouldn’t have gotten hired if they didn’t happen to live on the right side of the state line. If you want protectionism in your schools and public services,  you’re going get lower quality schools and public services.