Washington (CNN) Eighteen state attorneys general filed a lawsuit Tuesday challenging Education Secretary Betsy DeVos over the department's lack of implementation of an Obama-era rule that was designed to protect students at for-profit colleges.

"From delaying student loan forgiveness to exposing students to misconduct by abusive schools, Secretary DeVos and the Department of Education have put special interests before students' best interests," New York Attorney General Eric Schneiderman said in a statement. "Failing to implement the Gainful Employment Rule leaves students vulnerable to exploitation and fraud. If Washington won't defend students against predatory for-profit schools, we will."

The official complaint, led by Maryland Attorney General Brian Frosh and Pennsylvania Attorney General Josh Shapiro, was filed by 18 Democratic attorneys general in the US District Court for the District of Columbia.

The department announced in June it would "allow for additional time for institutions to comply with overly burdensome gainful employment regulations."

Gainful employment regulations were put in place during the Obama administration to try to increase accountability. The rules require for-profit schools and programs to help students prepare for "gainful employment in a recognized occupation," in order to receive federal funding, according to a fact sheet issued by the Department of Education in 2015.

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