U.S. Sen. James Lankford (R-Okla.) is asking federal education officials to provide legal justification for their interpretation of Title IX’s provisions related to sexual harassment and assault.

The Obama administration’s Education Department has aggressively pushed colleges and universities to address campus sexual harassment and violence by promptly investigating complaints of misconduct and sanctioning anyone found to have done wrong.

It’s a move that has been welcomed by many assault survivors and their advocates, who have been working for years to raise awareness about the largely hidden problem of sexual violence on college campuses.

But others on the nation’s college campuses, and in Congress, have criticized federal officials for overstepping their bounds, pressuring schools to create quasi-criminal justice systems on campus that fail to adequately protect the rights of the accused. And now their cause is being pushed by Sen. James Lankford (R-Okla.), who on Thursday sent a letter questioning whether the Education Department has exceeded its legal authority in its efforts to push colleges to do more on sexual assault.

Lankford, chairman of the Senate’s regulatory affairs subcommittee, argues that federal officials essentially violated the rules that outline how the government is supposed to make rules.

“I don’t have a sense that the Department of Education is mean or evil,” Lankford said in an interview. “My issue is you have to follow the rules and do this the right way.”

The Obama administration laid out universities’ and school districts’ obligations to address harassment and sexual violence in two key “Dear Colleague” letters, one issued in 2010 and one in 2011.

The letters helped to usher in sweeping changes on many campuses. But some of their provisions were controversial, including a list of acts that should constitute harassment, which was broad enough that some scholars said it would conflict with students’ First Amendment right to free speech.

Also, the department said that an accused student should be disciplined if the majority of the evidence suggested the student was guilty — an important departure from the beyond-a-reasonable-doubt legal standard that prosecutors must meet to convict someone in court.

The letters are considered administrative guidance, which agencies are supposed to use when they need to clarify regulations that already exist. But Lankford argued in his letter Thursday that the Education Department’s letters outlined such big and important changes that they amounted to new regulations.

And there’s a whole process for writing new regulations. That process involves soliciting and responding to public input. It usually takes a long time. It is often a headache. Lankford accused the Education Department of misusing guidance letters to circumvent that headache.

“We can’t just say this is hard, so I’m going to skip it,” he said.

The Education Department declined to comment on Lankford’s criticisms. “We have received the letter and look forward to responding,” spokesperson Dorie Nolt wrote in an email.

This is not the first time that the department has faced questions about its use of Dear Colleague letters, and officials in the past have said that the letters are appropriate because they clarify existing regulations stemming from Title IX, the federal law that protects students from sex discrimination — and therefore assault and harassment — in federally funded education programs.

“I do not make the law, but we explain it. It’s an explanation of what Title IX means,” Catherine E. Lhamon, assistant secretary for civil rights, told the Senate education committee in 2014. “This is not regulatory guidance.”

“I greatly disagree with that,” Sen. Lamar Alexander (R-Tenn.) shot back in a lengthy exchange about the matter. “You’re just making an edict without any chance for public comment.”

Regulations are legally binding. Letters are not. However, Lankford wrote Thursday, many university officials have complained that they have no choice: They are so dependent on the federal government, particularly for student loan support, that they feel they must do what the Education Department says — even if it’s technically a suggestion and not a command.

His letter — addressed to Acting Secretary John B. King Jr. in his first full week at the department’s helm — asks the department to cite the existing regulations that justify every mandate in the 2010 and 2011 “Dear Colleague” letters.

“Colleges and universities across the nation, in addition to prestigious legal scholars, government officials, and members of the U.S. Congress view the Dear Colleague letters as improperly issued guidance that require constitutionally questionable and ill-conceived policies — policies that fail to accomplish our common regulatory goals of school safety and gender equality in education as required by Title IX,” Lankford wrote. “Here, I present to you an opportunity to correct the muddled record.”

Read the entire letter:

Sen. Lankford letter to Education Department