Every US law student learns about aiding and abetting at some point in law school. Some cases are easy: if bank robbers use an app to get a ride share to pick them up and don’t disclose anything about their plan, the driver is just driving, not aiding and abetting. If, on the other hand, bank robbers hop into the back of a waiting getaway car, the driver is both driving and aiding and abetting bank robbery. But, what if things aren’t so clear? Where is the line between innocently providing a service and aiding and abetting? That has been a hot topic for the last several years.
Two years ago, the United States Supreme Court’s landmark decision in Twitter, Inc. v. Taamneh, 598 U.S. 471 (2023) established that aiding-and-abetting liability under the Anti-Terrorism Act (ATA) requires more than mere omissions, inactions, or nonfeasance; a defendant can be liable only where it “consciously and culpably participate[s] in [the] wrongful act so as to help make it succeed.” Twitter, 598 U.S. at 493 (internal quotation marks omitted).[1] This term, in Smith & Wesson Brands, Inc. v. Estados Unidos Mexicanos, 605 U.S. __, 2025 WL 1583281 (U.S. June 5, 2025), the Supreme Court revisited and elaborated on the standards applicable to aiding-and-abetting claims, albeit in the context of a statute other than the ATA.
Since Twitter, lower courts have grappled with how to implement the Supreme Court’s standard. The result has been disparate applications of Twitter’s guidance depending on whether a plaintiff pleads affirmative misconduct or passive nonfeasance. That disparity suggests the existence of substantial grounds for difference of opinion among trial-level courts regarding the proper application of the Twitter standard. The Supreme Court’s decision in Smith & Wesson, however, emphasizes the importance of an alleged aider-and-abettor’s intent regardless of which theory of liability is advanced. The Court reasoned that “[t]o aid and abet a crime, a person must take an affirmative act in furtherance of that offense. And he must intend to facilitate [the offense’s] commission.” 2025 WL 1583281, at *5 (internal quotation marks and citation omitted). In other words, an alleged aider-and-abettor “must ‘participate in’ a crime ‘as in something that he wishes to bring about’ and ‘seek by his action to make it succeed.’” Id. (quoting United States v. Peoni, 100 F.2d 401, 402 (2d Cir. 1938) (Hand, J.)) (emphasis added). Defendants in ATA cases, and companies operating in conflict zones and other geographical locations from which ATA claims spawn, should analyze the Smith & Wesson ruling carefully and monitor developments as trial-level and appellate courts implement its important guidance.
Background on ATA
The ATA, as amended by the Justice Against Sponsors of Terrorism Act (JASTA), creates a private right of action for U.S. nationals injured by an act of international terrorism to sue both the principal wrongdoers and those who aid and abet the terrorist act. Since JASTA’s enactment, aiding-and-abetting claims have proliferated against both foreign and domestic defendants.
Aiding-and-abetting claims under the ATA require a plaintiff to allege (i) the party whom the defendant aided performed a wrongful act that caused an injury; (ii) the defendant was generally aware of its role as part of an overall illegal or tortious activity; and (iii) the defendant knowingly and substantially assisted the principal violation. Lower courts considering ATA aiding-and-abetting claims post-Twitter have taken different views of the third element, in particular whether (and to what degree) a plaintiff must allege the defendant’s intent.
Background to the Smith & Wesson Case
Mexico maintains stringent laws around purchasing firearms: only one store in the entire country sells firearms and fewer than 50 gun permits are issued annually. Nevertheless, violent drug cartels and other organized gangs have perpetrated what the Mexican government has deemed an “epidemic of gun violence in Mexico” using guns that are manufactured in the United States and smuggled into Mexico.
In an effort to curb the flow of firearms across its northern border, the Mexican government filed a sweeping 135-page lawsuit in U.S. federal court against seven major American firearm manufacturers that allegedly make most of the trafficked guns. Mexico contended that the gun manufacturers were aware that ‘bad-apple’ retail gun dealers were unlawfully selling the manufacturers’ guns, which were then funneled to drug cartels and other criminals in Mexico, yet failed to implement adequate preventative measures. The complaint alleged that the companies therefore aided and abetted the illegal trafficking of firearms to Mexico and should be held liable for the harms arising from the firearms’ use by cartels and other criminals. The complaint sought billions of dollars in damages as well as an injunction designed to halt the alleged firearm trafficking.
The principal hurdle for Mexico’s lawsuit was the Protection of Lawsuit Commerce in Arms Act (PLCAA), which generally shields firearm manufacturers from liability for harms caused by third parties’ criminal use of their products. However, Mexico sought to invoke an exception in the PLCAA that permits plaintiffs to pursue common law claims—such as aiding and abetting other people’s firearms offenses—against gunmakers. The district court dismissed the lawsuit but the First Circuit reversed, holding that Mexico plausibly alleged that the defendants aided and abetted illegal firearms sales within the scope of the PLCAA exception.
The Supreme Court’s Aiding-and-Abetting Analysis
In a unanimous opinion authored by Justice Kagan, the Supreme Court ruled in favor of the firearms companies because the complaint did not plausibly allege that the gun manufacturers aided and abetted illegal firearm sales. Although the Court had “little doubt” that firearm manufacturers are aware that some illegal sales occur, Mexico did not adequately plead that the manufacturers intended to facilitate or ensure the success of those unlawful transactions. Smith & Wesson, 2025 WL 1583281, at *7. At the outset, the Court said that the complaint lacked allegations regarding specific illegal firearm sales. Instead, the complaint “level[ed] a more general accusation: that all the manufacturers assist some number of unidentified rogue gun dealers in making a host of firearms sales in violation of various legal bars.” Id. Thus, the Court declared that Mexico’s complaint faced a high bar: it had to plausibly allege that the firearm manufacturers provided pervasive, systemic and culpable assistance to gun traffickers.
The Court also underscored that intent is critical in assessing aiding-and-abetting claims: an aider-and-abettor must “intend to facilitate [the offense’s] commission” and “must ‘participate in’ a crime ‘as in something that he wishes to bring about’ and ‘seek by his action to make it succeed.’” Id. at *5 (quoting Peoni, 100 F.2d at 402) (emphasis added).
Relatedly, the Court elaborated on the element that Twitter flagged as indicative of intent and culpability. Twitter stated that providing routine services “in an unusual way . . . could constitute aiding and abetting” wrongdoing. 598 U.S. at 502. In support Twitter cited only Direct Sales Co. v. United States, 319 U.S. 703 (1943). Id.
In Smith & Wesson, the Court reiterated the significance of Direct Sales for the culpability analysis. It explained that in Direct Sales, the defendant pharmacy “sold huge amounts of morphine” to a doctor and “actively stimulated” the doctor’s purchases “by giving him special discounts for his most massive orders and using high-pressure sales methods.” Smith & Wesson, 2025 WL 1583281, at *6 (internal quotation marks omitted). The Court illustrated that the amounts of morphine involved could only have illegitimate uses: the “average physician required no more than 400 quarter-grain tablets annually,” but the defendant sold the doctor “some 5,000 to 6,000 half-grain tablets every month.” Id. And it did all of this “against the backdrop of law enforcement warnings.” Id.
According to the Court, the unusual nature of the morphine orders in Direct Sales illustrated that the defendant “‘not only kn[ew of] and acquiesce[d]’ in [the doctor’s] ‘illicit enterprise,’ but ‘join[ed] both mind and hand with him to make its accomplishment possible.’” Id. (quoting Direct Sales, 319 U.S. at 713). In other words, the Court again came back to intent: the pharmacy’s unusual business was culpable because the pharmacy intended to make the doctor’s illicit drug-dealing succeed.
By contrast, in Smith & Wesson, Mexico did not plausibly allege “the kind of ‘conscious ... and culpable participation in another’s wrongdoing’ needed to make out an aiding-and-abetting charge.” Id. at *5 (quoting Twitter, 598 U.S. at 493). Mexico’s complaint did not claim that the manufacturers conducted “unusual” business or treated ‘bad-apple’ gun dealers more favorably than law-abiding dealers: rather, it “repeatedly states that the manufacturers treat rogue dealers just the same as they do law-abiding ones—selling to everyone, and on equivalent terms.” Id. at *7. Additionally, unlike the direct transactions in Direct Sales between the pharmacy and doctor, the firearm manufacturers sold firearms to middlemen distributors, who in turn sold to the dealers. In the Court’s view, Mexico did not “offer some reason to believe that the manufacturers attend to the conduct of individual gun dealers, two levels down.” Id.
The Court likened the firearm manufacturers to the social media companies in Twitter. The plaintiffs in Twitter accused the social media companies of insufficiently identifying and removing ISIS supporters from their platforms. However, the plaintiffs did not allege that the companies provided ISIS any special treatment that they did not give to their billion-plus other users. The companies simply provided their platforms for general use and “at most allegedly stood back and watched.” Twitter, 598 U.S. at 499. Twitter held that more was needed, such as the conduct in Direct Sales, for a provider of generally available goods or services to be liable for a bad actor’s misuse of them. Mere knowledge that some unidentified bad actors are making illegal use of its wares would not trigger aiding-and-abetting liability for the company.
In this case, although Mexico alleged that the firearm manufacturers were aware that some retailers engaged in illegal gun sales and that the manufacturers “could do more than they do to figure out who those rogue dealers are, and then to cut off their supply of guns” (Smith & Wesson, 2025 WL 1583281, at *8), the Court characterized Mexico’s claims as reflecting “indifference, rather than assistance.” Id. (internal quotation marks omitted). The Court further found that the manufacturers’ decisions not to take actions beyond what federal law requires amounted to “omissions” and “inactions,” which “are rarely the stuff of aiding-and-abetting liability.” Id. Accordingly, the Court held that the manufacturers could not be held liable for the downstream harms caused by the misuse of their products in Mexico.
Takeaways
Smith & Wesson further illustrates the types of factual allegations that plaintiffs, including in the ATA context, need to plead to state an aiding-and-abetting claim. ATA litigants already have begun to submit the Smith & Wesson decision as supplemental authority, and it is likely that future motion-to-dismiss briefing will invoke Smith & Wesson’s analysis as a basis for dismissal. It remains to be seen how lower courts implement Twitter, as supplemented by Smith & Wesson, but much attention is likely to be paid to whether an ATA defendant’s alleged conduct closely resembles the ‘active incitement’ of the pharmacy in Direct Sales. Regardless, the Supreme Court was quite clear that aiding-and-abetting liability should be limited to those instances where the allegations demonstrate a defendant’s intent to facilitate the wrongful conduct’s commission.
[1] Supreme Court Resets Aiding and Abetting Liability Threshold in Anti-Terrorism Act Cases.
