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The Justice Department is reviewing Oakland Mayor Libby Schaaf’s “outrageous” warning to the community ahead of a large-scale operation by federal immigration authorities, the White House said Thursday.

“I think it’s outrageous that a mayor would circumvent federal authorities and certainly put them in danger by making a move such as that. And that’s currently under review by the Department of Justice, and I don’t have anything else to add,” press secretary Sarah Huckabee Sanders said in her afternoon briefing at the White House.

Schaaf said she issued the alert Saturday night after receiving confidential tips that U.S. Immigration and Customs Enforcement, known as ICE, was planning arrests across the Bay Area. Her spokesman, Justin Berton, said Thursday that she was not aware of the review mentioned by Huckabee Sanders.

More than 150 people were detained in the sweep, but ICE Acting Director Thomas Homan blamed Schaaf for helping hundreds more evade agents. He compared the mayor’s alert to “a gang lookout yelling ‘police.’”

Back to Gallery White House slams Oakland Mayor Libby Schaaf’s warning... 8 1 of 8 Photo: Scott Strazzante / The Chronicle 2018 2 of 8 Photo: NOAH BERGER, NYT 3 of 8 Photo: Ben Margot, Associated Press 4 of 8 Photo: Scott Strazzante, The Chronicle 5 of 8 Photo: Scott Strazzante / The Chronicle 6 of 8 Photo: Paul Chinn / The Chronicle 2017 7 of 8 Photo: Pool, Getty Images 8 of 8 Photo: Justin Sullivan, Getty Images















Legal experts said it was unlikely that Schaaf could be charged with obstruction of justice, noting that her weekend news release was vague and that proving a corrupt intent would be difficult.

“It can’t be a corrupt intent simply to have the desire for someone to avoid prosecution,” said Professor Robert Weisberg of Stanford Law School. “This is just going to be fought out between the feds and the locals, but I don’t think obstruction will come into play. How would this differ from somebody saying, ‘The San Francisco Police Department is using more resources to patrol neighborhood X for drugs’?”

Neither warning would be directly interfering with an investigation, and thus would not count as obstruction, Weisberg said.