If the next president’s immigration agenda includes a pitched battle over “sanctuary” cities, a term Donald Trump uses with disgust, the proper response from places like New York will be: Bring it on.

The word “sanctuary” as Mr. Trump deploys it — a place where immigrant criminals run amok, shielded from the long arm of federal law — is grossly misleading, because cities with “sanctuary” policies cannot obstruct federal enforcement and do not try to. Instead, they do what they can to welcome and support immigrants, including the unauthorized, and choose not to participate in deportation crackdowns they see as unjust, self-defeating and harmful to public safety.

New York City wears that kind of “sanctuary” label proudly. As California considers bold steps to shield its residents from a possible Trump immigration assault, the New York City Council has already built its own strong web of protections. A groundbreaking City Council program has provided free legal representation for children who fled violence in Central America and arrived unaccompanied at the border. Of 1,265 cases accepted under the program, 72 children were granted asylum and 55 obtained lawful permanent residency. The Council has expanded health and legal services in immigrant communities. And it passed bills to keep federal immigration agents out of the Rikers Island jails, and to forbid city police and corrections officers from detaining suspects for deportation, unless there is a judge’s warrant.