The American Federation of Teachers, one of the country’s biggest teachers unions, sued Education Secretary Betsy DeVos on Wednesday, alleging her agency took unlawful shortcuts when repealing restrictions on the debt students amass in career-training programs.

The case centers on an Obama-era regulation that threatens to cut off federal student aid to vocational programs whose graduates consistently have high loan payments relative to their income. DeVos delayed enforcement of key provisions of the regulation, then suspended the rule and then proposed a rewrite before finally rescinding it in June.

The teachers union asserts that the repeal was hastily executed without adequate opportunity for public comment and based on unfounded assertions. The group says DeVos and the Education Department acted arbitrarily in violation of federal law and placed college students in danger of being preyed upon by bad actors.

“It’s telling that Betsy DeVos, when confronted with the biggest student debt disaster in American history, decides once again to side with profiteers, not borrowers,” American Federation of Teachers President Randi Weingarten said in a statement. “This error-ridden repeal would be comical if the stakes weren’t so high, but for borrowers confronting a lifetime of debt and worthless degrees, their lives are literally on the line.”

Dan Zibel, an attorney representing the union, said the Education Department has an obligation to explain its decisions and changes it has made but failed to do so in this instance. While the rationale for the 2014 rule, known as “gainful employment,” included robust data supporting the regulation, the 2019 repeal did not, he said. Zibel is chief counsel at the National Student Legal Defense Network, which was founded by lawyers who worked in the Education Department under President Barack Obama.

Education Department spokeswoman Angela Morabito said the agency will “vigorously defend its final regulation rescinding this deeply flawed rule.”

DeVos has criticized the Obama-era rule for targeting for-profit colleges, arguing that no one group should be subject to heightened regulation.

The rule covers vocational education at a variety of institutions, but for-profit colleges have been vehemently opposed because many of their programs were at risk. When the Obama administration issued the rule in 2014, it had identified 1,400 programs serving 840,000 students that would not meet its accountability standards. About 99 percent were at for-profit colleges.

Supporters of the regulation say it is a safeguard against schools charging tens of thousands of dollars for programs that cost more than graduates will ever make annually. The regulation also required schools to inform current and prospective students of total costs, completion rates, graduate earnings and whether they are falling short of the rule.

Shortly after the rule took effect, many colleges eliminated their worst-performing programs, froze tuition and instituted other reforms to improve graduate outcomes. Without the threat of sanctions, proponents of the regulation say, there will be no accountability.

The Trump administration has released more data about academic programs through the College Scorecard website, but schools are not taken to task for poor outcomes.

The union is asking the courts to reinstate the regulation. Attorneys for the group say restoring the rule could save taxpayers $5.3 billion by ending the flow of federal funds to failing programs based on the Education Department’s own estimates.