May 21, 2020 MEMBER OP-ED

Comcast Offers Clarity on Causation Standard, But Questions Remain

by Sandra Sperino

On March 23, 2020, the Supreme Court announced its opinion in Comcast v. National Association of African-American Owned Media. The Court held that a plaintiff is required to establish “but for” cause to prevail on a claim under 42 U.S.C. § 1981. Surprisingly, the opinion is joined by all of the Justices.

This article discusses the holding in Comcast, its implications, and the questions the case leaves unanswered. 


Entertainment Studios Network (ESN) and the National Association of African-American Owned Media sued Comcast, arguing that Comcast refused to carry ESN’s programming based on race, thus violating 42 U.S.C. § 1981. That statute guarantees “all persons . . .the same right . . . to make and enforce contracts . . . as is enjoyed by white citizens.”

The federal trial court granted Comcast’s motion to dismiss the case. The United States Court of Appeals for the Ninth Circuit reversed, finding that the plaintiffs had provided plausible facts to suggest that race played some role in the outcome. The Supreme Court vacated the Ninth Circuit and remanded the case so that the Ninth Circuit could reconsider its decision using the new legal standard articulated by the Supreme Court.

In Comcast, the Court considered the proper causal standard under section 1981.

The Comcast Holding

In Comcast, the Court held that a plaintiff in a discrimination case must establish that a protected trait was a “but for” cause of an outcome. Justice Gorsuch delivered the opinion of the Court.

The reasoning in Comcast largely replays the arguments adopted in University of Texas Southwestern Medical Center v. Nassar and Gross v. FBL Financial Services, Inc. In Gross, the Court held that a plaintiff is required to establish “but for” cause to prevail on a claim under the Age Discrimination in Employment Act. In Nassar, the Court held that a plaintiff is required to establish “but for” cause to prevail on a retaliation claim under Title VII.

In Comcast, the Court begins with the fairly uncontroversial proposition that in tort law, a plaintiff must typically prove causation. The Court then noted that the typical causation standard is “but for” cause.

After noting these basic points of law, the opinion wades onto more controversial ground.  The Court assumed that a statute requires a plaintiff to establish “but for” cause unless the statute either explicitly or implicitly provided otherwise.  The Court found no such exception within the text or history of Section 1981.

The Court recognized that the text of Section 1981 does not explicitly contain causal language like the causal language typically used in tort law. The statute guarantees “all persons . . .the same right . . . to make and enforce contracts . . . as is enjoyed by white citizens.” The Court stated that this language was “suggestive” of a “but for” causation standard.  The Court also claimed that the history of Section 1981 supported its holding.

The Court also claimed that its treatment of Section 1982 claims supported its interpretation of Section 1981 claims. It cited Buchanan v. Warley for the proposition that a plaintiff proceeding under Section 1982 must show that a citizen was not allowed to acquire property “because of” his race. However, that case only discussed causation in a general sense and did not specify which causal standard should apply in Section 1982 cases. While Buchanan supports the idea that causation is an element of a Section 1982 case, it does not stand for the more specific concept that the plaintiff is required to establish “but for” cause.

The Supreme Court also drew support for its holding from the 1991 amendments to Title VII and the lack of a similar amendment to Section 1981. In 1991, Congress amended Title VII in response to Price Waterhouse v. Hopkins. In Price Waterhouse, the Supreme Court interpreted the causal language in Title VII to require the plaintiff to establish her protected trait was a “motivating factor” in an outcome. However, the Court allowed the employer to escape liability completely through an affirmative defense. If the employer established that it would have reached the same outcome without considering the plaintiff’s protected trait, the employer would prevail.

Congress believed that this affirmative defense was too employer-friendly. In 1991, Congress amended Title VII to make it more worker-friendly than Price Waterhouse. Congress explicitly included the motivating factor language within Title VII, but changed the affirmative defense from a complete defense to one that limited damages.

When Congress amended Title VII in 1991, it did not amend Section 1981 in a similar way. In Gross, the Court used Congress’ failure to amend the ADEA with similar provisions in 1991 to support the idea that Congress intentionally rejected the motivating factor standard for the ADEA. The Court used a similar argument in the Nassar case with respect to Title VII’s retaliation provision. In Comcast, the Court reiterated this same argument with respect to Section 1981.

During Comcast, the respondents argued that the causal standard might be different depending on the procedural posture of the case. The Supreme Court held that the required causal standard remains the same, even at different procedural stages. In other words, a plaintiff at the motion to dismiss stage must allege facts plausibly suggesting that the plaintiff can establish a protected trait was a “but for” cause of the challenged outcome. The Court noted that the kinds of materials that litigants would use to support or undermine causation might vary according to the procedural posture of the case. It is also worth noting that the procedural posture of the case also dictates how a court must view the evidence submitted by each party.

Unanimous Opinion Is a Surprise

The most surprising aspect of Comcast is the fact that it is unanimous. Justices Ginsburg, Sotomayor, Breyer, and Kagan joined the opinion, even though all four of these Justices dissented in Nassar in 2013. Justices Ginsburg and Breyer dissented in Gross in 2009. Justices Kagan and Sotomayor joined the Court after Gross was argued.

In the Nassar dissent, these four Justices argued that the 1991 amendments to Title VII strengthened Title VII and made it more worker-friendly. These Justices argued that it was inappropriate to view Title VII’s 1991 amendments as weakening other aspects of discrimination law. The effect of the 1991 amendments provided in the Nassar dissent conflicts with the reasoning adopted by the Court in Comcast.

The holding in Comcast relies heavily on the idea that tort law would require a plaintiff to prove “but for” cause. However, the Nassar dissent described how the Supreme Court rejected this same argument in Price Waterhouse. Additionally, the dissent argued that if the Title VII “motivating factor” standard and affirmative defense provisions did not apply to retaliation claims, then the default understanding of causation should be the one adopted by the Supreme Court in Price Waterhouse.

The Court’s reasoning in Comcast relies heavily on two propositions: (1) that it is appropriate to apply tort common law to federal statutes and (2) that tort common law requires the plaintiff to establish “but for” cause. The Nassar dissent rejected the idea that it was appropriate to import this tort concept into discrimination law. The dissent noted that “but for” cause was developed to explain the causal connections of physical forces and that it was difficult to use this concept to explain discrimination cases, which often rely on motive, intent, or animus.

Justices Breyer and Ginsburg joined both dissents in Gross. These dissents argued that Price Waterhouse set the applicable precedent and that a plaintiff should be able to prevail on an ADEA claim by establishing that her age was a “motivating factor” in an outcome. They also argued that “but for” cause imposes an impoverished version of causation on employment discrimination law. They argued that the 1991 amendments to Title VII do not reflect a congressional intent to weaken other discrimination statutes.

Unanswered Questions Related to Causation

Comcast leaves two areas of potential uncertainty related to causation: how district and appellate courts will apply the new causal standard and whether courts can use other causal frameworks in some instances.

Applying the New Causal Standard

The true impact of Comcast will only be known when appellate and district courts apply the new standard in Section 1981 cases. In most cases, whether a trial court applies a “but for” cause standard or a “motivating factor” standard should not impact how a federal judge rules on motions to dismiss or motions for summary judgment.

Fed.R.Civ. P. 12(b)(6) provides the standard for motions to dismiss based on failure to state a claim, and Fed.R.Civ.P. 56 provides the standard for summary judgment motions. In discrimination cases, the defendant is typically the party moving for summary judgment or to dismiss the case. The procedural rules for these motions require federal courts to view all evidence and inferences to be drawn from the evidence in favor of the non-moving party.  The non-moving party is typically the plaintiff.

Given these procedural standards, it will often be inappropriate for a court to dismiss a case or grant summary judgment for the defendant based on the new causal standard. If a plaintiff has evidence that a protected trait played a role in an outcome, it will often be impossible to determine exactly what role the protected trait played at the motion to dismiss and summary judgment stages. 

Take the following example. A plaintiff claims her employer fired her because of her race and presents evidence to support her claim. The employer claims it fired her because she was late for work three times. At least three possible causal paths emerge from these facts: (1) the employer acted because of race; (2) the employer acted because of the employee’s tardiness; or (3) the employer acted because of some combination of the employee’s race and the fact that she was late.  In most cases, it will be difficult to a declare (consistent with the procedural posture) that a plaintiff will be unable to establish “but for” cause.

However, the causal standard applied in discrimination cases has been contested for decades. This is, in part, because in practice, the causal standard does play a role in whether courts dismiss cases. Some courts improperly equate “but for” cause with sole cause. This is despite the Supreme Court’s explicit instruction that “but for” cause and sole cause are two different causal standards.

Other courts have struggled with the concept that there can be more than one “but for” cause to an outcome. When describing “but for” cause, courts often state that the protected trait must be the “but for” cause of an outcome. Use of the word “the” gives the misimpression that there can only be one “but for” cause.

The Supreme Court has made it clear that a party can establish “but for” cause when multiple causes exist. In Burrage v. U.S., the Court noted:

Thus, “where A shoots B, who is hit and dies, we can say that A [actually] caused B’s death, since but for A’s conduct B would not have died.” LaFave 467–468 (italics omitted). The same conclusion follows if the predicate act combines with other factors to produce the result, so long as the other factors alone would not have done so—if, so to speak, it was the straw that broke the camel’s back. Thus, if poison is administered to a man debilitated by multiple diseases, it is a but-for cause of his death even if those diseases played a part in his demise, so long as, without the incremental effect of the poison, he would have lived.

“But for” cause means that the cause was a necessary condition of the harm. An act can be a necessary condition of harm even when multiple acts are necessary to cause the harm. The Restatement provides examples of when a plaintiff can establish “but for” cause even when multiple causes exist. In one Restatement hypothetical a child suffers a seizure after a vaccination. If there is evidence that the vaccination intersected with a prior traumatic injury to cause the seizure, both the vaccination and the prior injury can be the “but for” cause of the seizure.

This outcome comports with the outcome in McDonald v. Santa Fe Trail Transp. Co., a case in which two white workers alleged race discrimination. The employer claimed that the two employees were terminated after stealing property. The employees argued that the employer did not terminate a black employee who engaged in similar misconduct. In McDonald, the Supreme Court specifically rejected the argument that the plaintiffs could not prove race discrimination in a case where the “dismissal was based upon their commission of a serious criminal offense against their employer.” The Court noted, “While Santa Fe may decide that participation in a theft of cargo may render an employee unqualified for employment, this criterion must be applied, alike to members of all races, and Title VII is violated if, as petitioners alleged, it was not.”14

The ultimate impact of Comcast will depend on whether courts properly apply “but for” cause within the context of the procedural rules governing motions to dismiss and motions for summary judgment.

Possible Exceptions

After Comcast, it is also unclear if lower courts will be able to apply a “motivating factor” standard in cases where tort law would not apply “but for” cause. In Comcast, the Court claims to be applying tort causation to discrimination law.

While it is correct that “but for” cause is often the starting point for causation doctrine in a torts case, “but for” cause is not a stand-alone concept in tort law. Instead, it is part of a larger bundle of causal standards, that together form the common law notion of factual cause. It is not clear whether the Court in Comcast intends to apply tort law (which would allow for various causal standards) or whether it intends to impose a truncated version of tort law on the discrimination statutes.

The common law does not use “but for” cause alone, because doing so creates results that are unfair and that, in some cases, do not make sense. For example, tort law sometimes allows a partial burden shift to the defendant on causation issues and sometimes changes the substantive standard when “but for” cause produces strange results. Applying “but for” cause without the rest of the bundle is not consistent with the common law. Doing so places a higher factual cause standard on a plaintiff seeking a remedy under a federal civil rights statute than the common law would require.

In other cases, the Supreme Court described factual cause more completely.  It stated:

[T]he availability of alternative causal standards where circumstances warrant is, no less than the but-for test itself as a default, part of the background legal tradition against which Congress has legislated. It would be unacceptable to adopt a causal standard so strict that it would undermine congressional intent where neither the plain text of the statute nor legal tradition demands such an approach.16

It is not clear whether the Court will allow plaintiffs in particular cases to argue that the default “but for” standard is not appropriate given the particular facts of the case.

Comcast and McDonnell Douglas

The McDonnell Douglas test is a three-part burden-shifting framework that a plaintiff may use to establish discrimination. The Comcast case could have undermined the continued viability of McDonnell Douglas, but the opinion strongly suggests that plaintiffs may still establish discrimination claims through the test, even claims that require “but for” cause. 

In Comcast, the Court held that the plaintiff must establish causation and that the substantive standard for doing so is “but for” cause. The holding thus discussed two separate, but interrelated issues: the party that carries the burden of persuasion and the substantive standard that party is required to meet.

Since the Supreme Court decided Gross and Nassar, the lower courts have been considering whether a plaintiff may use McDonnell Douglas for causes of action that require the plaintiff to establish “but for” cause. The potential tension between McDonnell Douglas and “but for” cause exists for two reasons.

First, McDonnell Douglas does not clearly and explicitly articulate a causal standard in the same way that Gross, Nassar, and Comcast do. Second, once the plaintiff establishes a prima facie case under McDonnell Douglas, the burden of production shifts to the defendant to articulate a legitimate, non-discriminatory reason for acting. The burden of production does not remain with the plaintiff through the McDonnell Douglas test. Appellate courts have held that plaintiffs may establish “but for” cause by proceeding through the McDonnell Douglas analysis.

On page 12 of the Comcast opinion, the Court discusses how the case intersects with McDonnell Douglas. This portion of the opinion appears to be dicta, and it is not entirely clear what the Court is trying to convey.

The Court may have hinted that McDonnell Douglas may not apply in Section 1981 cases, but it is difficult to tell. The Court started a sentence with the following: “[w]hether or not McDonnell Douglas has some useful role to play” in Section 1981 cases. It is not clear what this introductory phrase means.

The Court seems to leave McDonnell Douglas intact, while also cryptically noting that a plaintiff may not use the test to survive a motion to dismiss when the complaint fails to allege essential elements of a claim. The Court noted that McDonnell Douglas only shifts the burden of production to the defendant. The Court may be hinting that since the burden of persuasion always remains with the plaintiff, that the slight shift of the burden of production in step two of McDonnell Douglas does not contradict the Comcast holding that the plaintiff bears the burden of persuasion.

Comcast does not discuss how to square the substantive “but for” cause standard with McDonnell Douglas. However, prior to Comcast, the Supreme Court has indirectly discussed the intersection of “but for” cause and McDonnell Douglas in the discrimination context. In Furnco Construction Corp. v. Waters, the Supreme Court explained that a McDonnell Douglas prima facie showing “is simply proof of actions taken by the employer from which we infer discriminatory animus because experience has proved that in the absence of any other explanation it is more likely than not that those actions were bottomed on impermissible considerations.”

Likewise, in St. Mary’s Honor Ctr. v. Hicks, the Court noted that if the plaintiff established a prima facie case and the defendant did not properly respond, then judgment in the plaintiff’s favor is appropriate. In other words, if a plaintiff proves the prima facie case and the defendant does not respond, the plaintiff has submitted all the evidence needed to prove that the employee’s protected trait was the cause of the challenged outcome. These cases stand for the proposition that a plaintiff may establish causation through the prima facie case because the prima facie case creates a presumption that discrimination is the reason for the outcome.

At the third step of McDonnell Douglas, proof of pretext can also establish “but for” cause, as such evidence allows the factfinder to infer that discrimination is the likely reason for the outcome. It is worth noting that “but for” cause does not require a plaintiff to establish sole causation, “but only that the adverse action would not have occurred in the absence of” the protected trait.

Current McDonnell Douglas doctrine would allow a plaintiff to establish “but for” cause either through the prima facie case or through pretext. If a plaintiff can establish the prima facie case, this creates a rebuttable presumption that a protected trait was the cause of the action.  Similarly, if a factfinder finds pretext, the factfinder may find that the protected trait was the cause of the challenged action.

    Sandra Sperino is the Judge Joseph P. Kinneary Professor of Law at the University of Cincinnati College of Law, where she teaches and writes in the areas of employment discrimination, torts, and civil procedure.