Janet Napolitano, president of the University of California, knows exactly what’s at stake if President Trump shuts down an Obama administration program that has given work permits and protection from deportation to some 752,000 young undocumented immigrants. In 2012, in her previous job as secretary of Homeland Security, she signed the document — nothing more than a policy memo — that created the program.

So when alarm spread among immigrants on college campuses following Mr. Trump’s election, Ms. Napolitano moved quickly to determine what the California system could do to shelter its students if he carried through on his pledges to cancel the program, Deferred Action for Childhood Arrivals. The university estimates that almost 3,800 among its 190,000 students are undocumented, many but not all with DACA.

Ms. Napolitano, retaining her law enforcement instincts, does not mention the word “sanctuary” when describing what the university could offer. “Sanctuary is such a vague term, we don’t use it,” she said crisply.

Instead, the university has published detailed principles of support for undocumented students, including assurances that campus police would not question students solely about their immigration status or join any cooperation agreements with federal immigration authorities under the Trump administration. Through the Davis campus law school, the university is organizing legal help for students detained for deportation.