WASHINGTON, D.C. — Supreme Court justices grilled lawyers for Byron Allen and Comcast on Wednesday over the right legal standard for evaluating the racial discrimination claims made in Allen’s 2015 lawsuit against the cable giant.

Chief Justice John Roberts and Justices Elena Kagan, Sonia Sotomayor, Neil Gorsuch, Stephen Breyer, Samuel Alito and Brett Kavanaugh engaged in spirited questioning of both sides. Justice Ruth Bader Ginsburg was the only one of the nine justices not in attendance. Roberts said at the start of the hourlong hearing that Ginsburg was “indisposed due to illness,” but would still participate in the decision by considering the briefs and reading the transcripts.

The justices spent a good deal of time quizzing the lawyers about the distinction between the two key tests for the case at issue before the court. Allen’s team, led by Erwin Chemerinsky, argued that the plaintiff should only have to demonstrate a plausible case that race was a “motivating factor” in Comcast’s decision to not to carry the group of cable channels owned by Allen’s Entertainment Studios for the case to move forward. Comcast argued that legal precedent demands that Allen should have to prove that the case meets a stronger “but-for” test, meaning that but for the fact of racial animus, Comcast would have done a carriage deal with Entertainment Studios.

There was also discussion of which side would have the burden of proving that racial animus was the but-for cause of Comcast not doing business with Allen. The concept of burden-shifting being applied to the case would mean that Comcast could present race-neutral reasons for its business decisions, to which Allen would then have to demonstrate that those were a pretext for discrimination.

At times the justices seemed unconvinced that the distinction between motivating factor and but-for was significant given that key facts would ultimately have to be proven at trial. Roberts’ first question for Comcast attorney Miguel Estrada was whether “the distinction you’re fighting is somewhat academic.”

Breyer was even more blunt. “What’s the difference,” he said. “Who cares whether (plaintiffs) say it is a motivating factor or whether they say it is a but-for,” at the complaint stage, he said. Chemerinsky’s response was that it is a much higher burden of proof on the plaintiff to commit to demonstrating but-for causation. At the same time, several justices asserted that for a plaintiff to prevail, a but-for test would likely have to be met by the end of trial.

“In fact, they are going to have to prove but-for causation at the end. And the question here is really what they have to allege now,” Kagan said. Later in the hearing she questioned whether the distinction needed to be made at the pleading stage.

“Why do you have to label that anything? Why do you just have to say those are the kinds of facts that at this stage of the litigation allow the — the complaint to go forward?” Kagan asked Chemerinsky.

Allen’s case was dismissed three times by lower U.S. district courts, but that was reversed on appeal by the Ninth Circuit last year. The appellate court ruled that for the case to proceed, Allen only had to demonstrate plausible claims that race was a motivating factor in Comcast’s decision.

Kavanaugh suggested that one plausible remedy would be for the high court to weigh in on the appropriate test, vacate the Ninth Circuit’s appellate decision and send the case back for further proceedings.

Estrada, of Gibson, Dunn & Crutcher, opened by arguing that the “but-for” causation standard has been a bedrock of the 1866 civil rights law invoked in Allen’s case — a federal statute known as Section 1981 that ensures that all American should have “the same right to make and enforce contracts as is enjoyed by white citizens.”

Chemerinsky pressed the point that if race in even a motivating factor for a company’s decision-making, then Section 1981 has been violated because the plaintiff would not have had the same rights in the process of contracting as a white person. Sotomayor keyed in on that distinction, going to so far as to read the definition of “making” from the dictionary as “the process of being made.”

Sotomayor invoked claims from Allen’s complaint that Entertainment Studios was instructed by Comcast executives to take certain steps that would make the channels more desirable to the cable operator, but to no avail.

“How can it be that if you’re treated differently because of your race in the formation of the contract, but you’re denied the contract for another reason, that other people may have been denied for, but you were treated differently, more burdens were put on you, more expenses were put on you, and at the end, they say, eh, you know, we really would never take on anyone like you with your business because, and it’s true, nobody with your business plan has been accepted before, but you’ve been run around in circles and made to expend a lot of money — why is that not actionable?” Sotomayor said. “As long as you have enough in your complaint to show racial animus and a reasonable inference can be drawn that that’s a but-for cause, I think a plaintiff has done more than enough” for the case to proceed.

Gorsuch and Chemerinsky had a testy exchange toward the end of the hearing as the sides parsed the significance of the court affirming the motivating factor standard even if the but-for cause would have to be proved at trial. Gorsuch and Kagan argued that as a matter of law, the Ninth Circuit appellate decision would have to be overturned because it asserts that motivating factor is enough for a plaintiff to prevail — something that Chemerinsky had agreed with.

The justices pushed Chemerinsky on the question of whether he was pushing for the motivating factor test in order to keep legal options open for the case at trial, including how to tackle the question of where the burden of proof would fall.

Gorsuch pushed Chemerinsky to give a yes or no answer to whether the Ninth Circuit decision needed to be overturned. When Chemerinsky tap-danced around the issue, Gorsuch cut him off curtly: “I’ve got it. We’re not going to get an answer,” he said.

Kavanaugh questioned Chemerinsky on his argument that the but-for test should not be a requirement for the case.

“These cases, as you know, are not usually thrown out at the motion to dismiss stage and usually you have the ultimate legal test in mind, and you just look at the facts alleged in the complaint to see, as Justice Sotomayor rightly said, whether there’s a way you could plausibly infer from those facts that it would ultimately meet the test for (Section) 1981 or for discrimination,” Kavanaugh said.

Several justices parried with Estrada on the question of how much but-for causation is baked into Section 1981 and other civil rights laws. Estrada pointed out that Congress has made changes to other civil rights laws to specify a “motivating factor” standard for discrimination laws but did not amend Section 1981 to do so, even though Congress has made other changes to Section 1981.

Estrada argued that to accept motivating factor for Section 1981 would “completely displace the carefully tailored regime” established by Congress in Title 7 of the 1964 Civil Rights Act that prohibits employers from discriminating on the basis of sex, race, national origin and religion.

Toward the end of the hearing, Alito raised the question of whether the lower court dismissals of the case were influenced by allegations in the complaint that Comcast “entered in to a racist conspiracy” with the NAACP, the Urban League and others as a means of covering up discriminatory practices.

Roberts sounded incredulous when referencing those claims in discussion how lower courts evaluated the plausibility of Allen’s complaint in its totality. While there are allegations in the original 2015 complaint that plausibly suggest that race may have been a factor in Comcast’s dealings with Allen, Roberts questioned whether it is “also enough to allege that the NAACP and the National Urban League and the other individuals were in on the conspiracy?”

Chemerinsky maintained that the detail about Comcast’s dealings with NAACP, Rev. Al Sharpton and others were removed from amended versions of the complaint that were also subsequently dismissed. In his closing three-minute rebuttal to Chemerinsky, Estrada cited references to that strain of the argument that remain in the most recent version of the complaint.

Estrada punctuated his point that the extraordinary conspiracy allegations undercut Allen’s overall case.

“If in any planet that satisfies the plausibility standard on (past precedent for such cases), the civil justice system has real problems,” Estrada said.