The Department of Justice on Friday sent letters to nine so-called “sanctuary” jurisdictions, threatening to withhold grant funding unless they prove that they are complying with federal law.

Recipients must certify compliance before June 30 in order to receive certain grants for the fiscal year 2016, The New York Times reported.

Recipients of the letters reportedly included New York City, Chicago, New Orleans, Philadelphia, Las Vegas, Milwaukee, the state of California, Miami-Dade County, and Cook County, Illinois.

Those same jurisdictions had been called out in a 2016 report by the DOJ’s inspector general as having local policies that may have impeded communications between local law enforcement agencies and federal officials regarding the immigration and citizenship statuses of inmates.

Under a 1996 federal law, 8 USC Section 1373, jurisdictions cannot prohibit local officials from withholding that information from federal authorities. Jurisdictions with “sanctuary” policies say they already follow that law, and the 2016 report did not find that any of the cities it reviewed had explicitly violated Section 1373.

The letters were signed by Alan Hanson, the acting director of the Office of Justice Programs, and closely echo remarks Attorney General Jeff Sessions made last month at a White House press briefing, at which he criticised sanctuary policies and urged jurisdictions to work with federal immigration agents in deporting unauthorised immigrants.

He said jurisdictions applying for DOJ grants must certify compliance with the law or risk the “withholding of grants, termination of grants, and disbarment or ineligibility for future grants.”

President Donald Trump signed an executive order in late January that said as much, although that has already been contested in federal court. Jurisdictions such as San Francisco and Santa Clara County are arguing that 8 USC Section 1373 violates the 10th Amendment and could deprive them of billions of dollars in federal funding.

Lawyers representing the Trump administration said, however, that any funding cuts would apply “only to a limited range of grants” and would not significantly affect those jurisdictions’ budgets.

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