FILE - In this May 18, 2017 file photo University of California President Janet Napolitano listens during a meeting of the Board of Regents in San Francisco. The University of California has sued the Trump administration over its decision to end a program protecting hundreds of thousands of young immigrants from deportation. The lawsuit filed on Friday, Sept. 8 in federal court in San Francisco includes university president Napolitano as a plaintiff.

AP Photo/Eric Risberg, File

SAN FRANCISCO — The University of California sued the Trump administration Friday over its decision to end a program protecting young immigrants from deportation, saying thousands of its students and some faculty would be affected if they are ordered to leave the country.

University President Janet Napolitano, who was Homeland Security secretary in the Obama administration and helped implement the Deferred Action for Childhood Arrivals program, is listed as a plaintiff in the lawsuit filed in federal court in San Francisco.

Napolitano said it's important for the public university system to stand up for members of its community.

"They represent the best of who we are — hard-working, resilient and motivated high achievers," she said. "To arbitrarily and capriciously end the DACA program, which benefits our country as a whole, is not only unlawful, it is contrary to our national values."

The program protects about 800,000 people who were brought to the U.S. illegally as children or came with families who overstayed visas. It currently includes hundreds of thousands of college-age students.

The lawsuit said the university will lose students and employees because of President Donald Trump's decision to end the program in six months if Congress doesn't take action first.

Attorney General Jeff Sessions has said President Barack Obama's decision to implement DACA was an unconstitutional exercise of his authority.

"While the plaintiffs in today's lawsuit may believe that an arbitrary circumvention of Congress is lawful, the Department of Justice looks forward to defending this Administration's position," DOJ spokesman Devin O'Malley said in a statement.

Fifteen states have sued separately over the president's decision, although California is not among them.

The UC system has about 4,000 students who are in the United States illegally, "a substantial number of whom have DACA, as well as teachers, researchers and health care providers who are DACA recipients," the university system said in a statement announcing the lawsuit.

Napolitano said the university system could pursue damages for interference with the relationship it has developed with its students and staff and for deprivation or interference with the investment it has made in students to give them an education.

In a conference call with reporters, she said there was no conflict between her previous role as Homeland Security secretary and her decision to file the lawsuit.

"It went through a careful legal analysis. No court has ever held that DACA was illegal and I believe it to be a legal exercise of prosecutorial discretion," Napolitano said. "There's no conflict and no thought of recusal."

Napolitano served as secretary of the Department of Homeland Security from 2009 to 2013, as governor of Arizona from 2003 to 2009, as Arizona's attorney general from 1998 to 2003, and as U.S. attorney for Arizona from 1993 to 1997.