Justice Department of the US has threatened to sue Harvard University to force it to turn over documents as it investigates whether the Ivy League school’s admission policies violate civil rights laws.

Citing a 2015 lawsuit that charges the school’s affirmative action policies discriminate against Asian-American applicants, the federal government in a letter set a Dec. 1 deadline for Harvard to hand over documents on its admission policies.

The Justice Department is probing the Cambridge, Massachusetts-based school’s compliance with Title VI of the 1964 Civil Rights Act, according to the letter, dated Friday and seen Reuters on Tuesday. The measure prohibits institutions that receive federal funding from discriminating based on race, color or national origin.

“The Department is left with no choice but to conclude that Harvard is out of compliance with its Title VI access obligations. Title VI does not allow entities under investigation to dictate what information qualifies as relevant” the letter reads.

The school said earlier this year that just over half of the freshmen admitted in 2017 were women, more than one in five was Asian and almost 15 percent African-American.