Somehow, law enforcement, both state and federal, managed to do its job without individual officers and agents concealing their identities. And then came ICE under Trump, where everything purportedly changed.

Gov. Gavin Newsom of California signed legislation on Saturday that would prevent federal immigration agents from wearing masks in the state, a direct response to President Trump’s deportation crackdown in the Los Angeles region.

The new law is believed to be the first such ban in the nation, though it is likely to be challenged in court before it can go into effect in January because it is unclear whether California can enforce such restrictions on federal law enforcement. The bill also applies to local law enforcement.

Masked and unidentified government agents seizing and using force against people in America, some of whom might be illegal aliens and others might be American citizens, raises some problems. Are they law enforcement or just pretending to be? If they violate someone’s constitutional rights, how would you seek redress if you have no way to identify them? And then there’s the big question, whether government law enforcement personnel should be concealing their identities at all, or whether they should have names, badge numbers and faces so the American public knows who is using force, including deadly force, against them?

“Comparing them to ‘secret police’ — likening them to the Gestapo — is despicable,” Tricia McLaughlin, a spokeswoman for the department, said in a statement. “Once again, sanctuary politicians are trying to outlaw officers wearing masks to protect themselves from being doxed and targeted by known and suspected terrorist sympathizers.”

On the one hand, why shouldn’t they be “doxed”? They cash United States government paychecks and if they’re doing the job that Americans want them to do, then others will applaud and thank them for their service. As for people who opposed masked agents violating the rights of others, calling them “suspected terrorist sympathizers” is no less vapid than calling the people in boats being murdered in international waters “narco-terrorists.” If so, then arrest and try them. You don’t get to make up a pretend label and kill them. At least you didn’t used to in America.

On the other hand, federal agents have been taking down terrorist and drug cartels for decades without wearing masks and being targeted for their work. The FBI, CIA, DEA, ATF, Postal Inspectors, have all put their lives on the line while showing their faces. Why is it different for ICE?

But can a state law bind federal agents?

Aya Gruber, a constitutional law professor at the University of Southern California, said that the mask law was likely to be immediately challenged along jurisdictional lines, and that the federal government would most likely seek an injunction to prevent the law from going into effect.

“It will definitely be challenged — 100 percent,” Ms. Gruber said, adding that she expected it to eventually be heard by the U.S. Supreme Court. “I don’t foresee this particular iteration of the Supreme Court taking the state’s side on this one, so this may be more of a symbolic piece of legislation.”

No doubt it will be challenged, but will this Supreme Court acquiesce to the government’s argument?

Erwin Chemerinsky, dean of the University of California, Berkeley School of Law, wrote a letter last week that urged Mr. Newsom to sign the legislation, which Mr. Chemerinsky said he believed was constitutional because it does not limit the federal government’s authority to perform its duties. Mr. Chemerinsky, a well-known constitutional scholar, said that even if a federal challenge was forthcoming, the state needed to make a forceful declaration against what he said was a practice intended to “terrorize” people.

Unsurprisingly, California law enforcement is against the law, not so much because they have any views about ICE agents, but because of its collateral impact on them.

Brian R. Marvel, the president of the Peace Officers Research Association of California, which represents over 87,000 public safety officers, said he was outraged by the passage of the law.

He said in a statement that he believed that California did not have the authority to regulate federal agents, so it would ultimately apply only to local law enforcement officers, which he called a “troubling betrayal that California’s local law enforcement community will not soon forget.” He said that limiting face coverings and opening officers up to prosecution would most likely hurt recruitment and drive officers from the state.

“This bill makes local officers collateral damage. It is a political stunt by all parties involved, plain and simple,” he said. “This bill will have a chilling effect on our profession.”

This raises two interesting issues. First, the new law would have no impact on local law enforcement unless local police plan to start concealing their faces and identities. Otherwise, it would have no impact at all. But now that they know ICE can get away with engaging in unconstitutional seizures and unjustified use of force with impunity, why not local cops too?

The second issue is that given the depth of antipathy toward the law, what are the chances that local police will enforce it against ICE agents even if the courts hold that it’s good law? One view is that California cops won’t know whether those masked people in body armor are federal agents or criminals until they detain them and ascertain their authority as federal agents. Will cops do that? If not, then there’s a law with nobody willing to enforce it. Yet another law.