A FEDERAL JUDGE on Sunday night issued a temporary injunction barring the federal government from moving ahead with an overhaul of the 52-year-old Fair Housing Act that would have increased the threshold tenants must meet to prove unintentional discrimination by landlords and mortgage lenders.

In his decision, Judge Mark Mastroianni of the US District Court of Massachusetts said the plaintiffs — the Massachusetts Fair Housing Center of Massachusetts and Housing Works of New York — “have shown a substantial likelihood of success on the merits” of one of their claims that the new rule is “arbitrary and capricious.”

The plaintiffs argued that the rule was improperly changed in a violation of the Administrative Procedures Act, which governs the process by which federal agencies develop and issue regulations.

The Fair Housing Act is a part of the Civil Rights Act of 1968, and prohibits discrimination in the sale, rental, or financing of dwellings and in other housing-related activities on the basis of race, color, religion, sex, disability, familial status, or national origin.

The Trump administration issued a new “disparate impact rule” that was scheduled to take effect on Monday. The rule would make it more difficult for people to prove they were discriminated against based on the impact of a policy or practice by housing providers, financial institutions, and insurance companies and the absence of an adequate justification.

Over 45,000 public comments were submitted on the proposed rule in August.

“As we face both a global pandemic and an ever-worsening housing crisis, it is imperative that our most vulnerable community members know there are robust legal protections to combat barriers to housing opportunity,” said Iván Espinoza-Madrigal, executive director of Lawyers for Civil Rights, which filed the suit on behalf of the plaintiffs in September.

The Justice Department filed a lawsuit in 2019, for instance, alleging that female residents of rental properties in Massachusetts were subjected to sexual harassment and retaliation, in violation of the federal Fair Housing Act. In 2018, HUD charged owners of a three-bedroom duplex in Wisconsin with discrimination for refusing to rent to a family with five children.

HUD in August said it was proposing the rule so the Housing Fairness Act would be more in line with a 2015 Supreme Court ruling that sought to clarify the application of the standard to state laws governing the business of insurance.

In that decision, the Supreme Court said policies segregating minorities in poorer neighborhoods, even unintentionally, violate the Fair Housing Act. The ruling did place limitations on the legal “disparate-impact” claim, saying that it should be applied carefully so that defendants don’t face abusive or extraneous accusations.

In 2017, more than 28,000 complaints of housing discrimination were filed across the country as violations of the FHA, according to the National Low Income Housing Coalition. Some of these complaints resulted in lawsuits against cities, banks, and landlords for discrimination in housing and lending.

“The court acted correctly and cautiously in pausing the implementation of a poorly drafted rule that would have thrown victims, advocates, and judges into chaos,” said Scott Lewis, a partner at Anderson & Kreiger, a law firm providing pro bono support with Lawyers for Civil Rights on District Court’s decision. “Staying the rule while the court holds a full adjudication on the merits protects our clients from irreparable harm and is in the public interest.”

Meris Bergquist, executive director of the Massachusetts Fair Housing Center, said the changes were a direct threat to the organization’s objective, which is to process and investigate claims of housing discrimination. “We accepted about 300 or so complaints last year,” she said. “One example is that we had a large landlord in our service area who is excluding applicants based on their criminal history.”

The organization serves Berkshire, Hampden, Hampshire, Franklin and Worcester counties. The rule changes under HUD created concerns about how that case and others would be adjudicated under the Fair Housing Act, Berquist said.

HUD did not reply to requests for comment on the Massachusetts courts’ decision.