UPDATED: December 30, 2014, at 5:43 p.m.

Harvard Law School has been found in violation of the federal anti-sex discrimination law Title IX for its “current and prior” sexual harassment policies and has agreed to revise its policies to comply with the law, the U.S. Department of Education’s Office for Civil Rights announced on Tuesday.

During the course of a years-long investigation into the Law School’s Title IX compliance, OCR found that the Law School “failed to comply with Title IX's requirements for prompt and equitable response” to complaints of alleged sexual harassment and sexual assault, referencing two student cases.

As a result of the violation, Harvard has entered a resolution agreement with OCR that will see the institutions work together to revise existing policies in accordance with federal guidelines. Under the agreement, the Law School must also make clear which of those policies and procedures apply to complaints at the Law School.

The development comes roughly four years after New England School of Law professor Wendy Murphy first filed a Title IX complaint against the Law School in 2010, spurring the investigation.

The agreement also comes just months after Harvard overhauled its approach to addressing sexual assault on campus. In July, administrators unveiled a new University-wide sexual harassment policy and set of accompanying procedures that took effect this fall. Among other points, the procedures created a new central office to investigate sexual harassment allegations across all of the University’s schools and adopted the OCR-preferred “preponderance of the evidence” standard of proof for determining guilt.

The new policy and procedures have proven controversial, particularly at the Law School. In October, more than two dozen Law School professors penned a letter to The Boston Globe protesting the changes, asserting that the proceedings “are overwhelmingly stacked against the accused and are in no way required by Title IX law or regulation.” Some student activists, meanwhile, have decried the policy’s lack of an explicit affirmative consent clause.

In September, the Law School adopted a set of interim procedures to comply with the new University-wide policy. According to a letter dated Tuesday and addressed to Law School Dean Martha Minow outlining the resolution agreement, OCR found that the new procedures addressed many of the problems the office had identified in the Law School’s previous sexual harassment policy. Specifically, the interim procedures implemented the “preponderance” standard of proof and allowed both complainants and respondents to “participate in decisions regarding possible sanctions.”

Still, OCR identified “deficiencies” in both the interim procedures at the Law School and in Harvard’s University-wide policy, according to the 18-page resolution letter. In particular, according to the agreement, the University must clarify its obligation to address incidents of sexual assault “that it knows or should know about” and to consider off-campus activities in evaluating the University environment. It must also add a statement to the policy that clearly outlines a complainant’s right to continue with both a criminal investigation and a Title IX investigation at the school.

The University’s policy must also assure that there will be no required mediation between the complainant and the accused in sexual harassment cases and that “both parties are to be provided an equal opportunity to participate in the process,” according to the letter. It additionally stipulates that the University-wide policy clarify that case decisions or fact-finding by the University cannot be overruled or altered by an individual school.

According to the resolution letter, the Law School on Dec. 18 adopted, but has not yet implemented, new Title IX procedures to replace its September interim procedures; those newly adopted policies are still under review. Until OCR reviews and approves them, the September interim procedures will remain the standard at the Law School.

The findings come after OCR spent years investigating the Law School’s compliance with Title IX. OCR concluded that the Law School responded inadequately to two student complaints filed under the Law School’s previous sexual harassment policy, in part because that policy used the “clear and convincing” evidence standard, which is considered to be a higher burden of proof than the “preponderance” standard now employed by the University and preferred by OCR.

Case timespan was also at issue: In one case, Law School administrators took more than a year to reach a final decision, and the student raising the complaint was also not allowed to take part in the extended appeals process. Eventually, the complaint was dismissed.

OCR’s investigation also concluded that the Law School failed to ensure that some administrators involved in the investigation of sexual assault complaints and policy negotiations, including Law School Administrative Board and faculty members, received adequate training.

As part of its resolution agreement with OCR, the Law School has agreed to train faculty, administrators, and staff about Title IX and conduct an annual campus survey to “ascertain the effectiveness of the steps taken to provide for a campus free of sexual harassment,” according to the Tuesday letter to Minow. The Law School will also review sexual harassment complaints filed during the 2012-2013 and 2013-2014 academic years to determine if those investigations were conducted in line with Title IX, according to the 10-page resolution agreement, which was reached Dec. 23.