More than two dozen civil rights groups said in briefs filed with the U.S. Supreme Court this week that a case involving Comcast Corp. and an African American Hollywood mogul could weaken discrimination protections in the workplace and deal a body blow to civil-rights laws.

Derrick Johnson, president and CEO of the NAACP, said Tuesday that the Comcast case had the potential for “irreparable harm” to the cause of civil rights. Other groups that filed briefs include the National Urban League and the National Action Network.

The Supreme Court has agreed to hear an appeal in the case involving Comcast and entertainment executive Byron Allen, who claimed in a federal lawsuit in California that Comcast racially discriminated against him when it refused to carry his cable-TV channels on its systems.

Legal experts say that at issue is whether a person filing a racial discrimination lawsuit must show that race is the “sole” reason a decision was made or whether race was “a motivating factor.”

Comcast said race had nothing to do with rejecting Allen’s channels, noting that they had low ratings. The Philadelphia company said the Allen case is a run-of-the-mill business dispute.

In response to an earlier NAACP statement, Comcast spokesperson Sena Fitzmaurice said in an email:

“This case arises from a frivolous discrimination claim that cannot detract from Comcast’s strong civil rights and diversity record or our outstanding record of supporting and fostering diverse programming from African American-owned channels.

“We have been forced to appeal this decision to defend against a meritless $20 billion claim, but have kept our argument narrowly focused. We are not seeking to roll back the civil rights laws — all we are asking is that the court apply Section 1981 in our case the same way it has been interpreted for decades across the country.”

But civil rights law professors and groups say that if the conservative-majority court decides in Comcast’s favor, it could make it harder for others to bring discrimination suits against companies based on civil rights laws passed immediately after the Civil War.

Kristen Clarke, president and executive director of the Lawyers’ Committee for Civil Rights Under Law, called the Comcast petition “the most important civil rights case to be heard by the Supreme Court in term. A negative ruling stands to all but shut the courthouse door on a vast number of victims of discrimination all across the country.”

Section 1981 of the Civil Rights Act of 1866 says all people in the United States have the same rights to make and enforce contracts “enjoyed by white citizens.” It was enacted to help newly freed African Americans engage in work fairly, without laws that created conditions that “paralleled chattel slavery,” according to the Lawyers’ Committee brief. “In light of the increasing visibility of minority populations, civil rights laws like Section 1981 must be strengthened, not weakened.... Petitioner [Comcast] asks this court also to ignore its past pronouncements and allow race to play some role in contracting decisions, so long as race discrimination is not the but-for cause of a refusal to contract.”

The Lawyers’ Committee brief represented 22 organizations, including the Anti-Defamation League, Asian Americans Advancing Justice, the Center for Constitutional Rights, the National Council of Jewish Women, the National Organization for Women Foundation, and the Southern Poverty Law Center.

The NAACP Legal Defense Fund filed a separate brief that included 10 other organizations, including the ACLU, the Mexican American Legal Defense and Educational Fund, and the National Women’s Law Center.

Comcast petitioned the Supreme Court after a decision in 2018 by the U.S. Court of Appeals for the Ninth Circuit in California that the company said loosened the standards on discrimination cases. Comcast was joined by pro-business groups, including the U.S. Chamber of Commerce, which filed supporting briefs arguing that looser standards in discrimination cases could lead to costly litigation and settlements.

The Trump administration’s Department of Justice also filed a brief supporting Comcast’s position on overturning the Ninth Circuit ruling.

“We are not proposing any radical changes in the law,” Miguel Estrada, partner in the Washington firm Gibson Dunn and counsel of record for Comcast in the case, said last month. “We are proposing that the Supreme Court restore the law to what other appeals courts have said it is. It is wrong to say that it will set back anything.”

Allen’s cable channels include JusticeCentral.TV and Comedy.TV. He owns 43 syndicated television series, eight cable networks, the Weather Channel, and a movie studio that distributed the film Chappaquiddick. He acquired the Weather Channel after filing his lawsuits; it is distributed on most cable systems. .

In early September, the head of the Los Angeles Urban League wrote to top Comcast officials saying he would call for a boycott of the cable giant if it did not withdraw its petition to overturn the Ninth Circuit ruling.

Michael A. Lawson, president and CEO of the Los Angeles chapter, said he wrote after the Trump administration’s brief supporting Comcast.

The court has scheduled arguments for the case for next monthin Washington.