False advertising under Lanham Act § 43(a) requires: (1) a false statement of fact by the defendant in a commercial advertisement about its own or another's product; (2) the statement actually deceived or has the tendency to deceive a substantial segment of its audience; (3) the deception is material, in that it is likely to influence the purchasing decision; (4) the defendant caused its false statement to enter interstate commerce; and (5) the plaintiff has been or is likely to be injured as a result of the false statement, either by direct diversion of sales from itself to defendant or by a lessening of the goodwill associated with its products. Southland Sod Farms v. Stover Seed Co., 108 F.3d 1134, 1139 (9th Cir. 1997); see also 15 U.S.C. § 1125(a). 

Literal falsity is one of the ways “[t]o demonstrate falsity within the meaning of the Lanham Act.” Southland Sod, 108 F.3d at 1139. Alternatively, a plaintiff may show that a statement was “literally true but likely to mislead or confuse consumers.” Id.; see, e.g., TrafficSchool.com, Inc. v. Edriver Inc., 653 F.3d 820, 829 (9th Cir. 2011); cf. Schering-Plough Healthcare Prods., Inc. v. Schwarz Pharma, Inc., 586 F.3d 500, 513 (7th Cir. 2009) (noting that a literal falsehood has to be “bald-faced, egregious, undeniable, over the top”). 

Literal falsity may be evaluated by (1) determining “the claim conveyed by the advertisement” and then (2) assessing whether this claim is literally false. Clorox Co. P.R. v. Proctor & Gamble Com. Co., 228 F.3d 24, 34 (1st Cir. 2000); accord Scotts Co. v. United Indus. Corp., 315 F.3d 264, 274 (4th Cir. 2002); Novartis Consumer Health, Inc. v. Johnson & Johnson-Merck Consumer Pharms. Co., 290 F.3d 578, 586 (3d Cir. 2002); Johnson & Johnson * Merck Consumer Pharms. Co. v. Smithkline Beecham Corp., 960 F.2d 294, 298 (2d Cir. 1992); see also Am. Council of Certified Podiatric Physicians & Surgeons v. Am. Bd. of Podiatric Surgery, Inc., 185 F.3d 606, 615 n.2 (6th Cir. 1999) (the truth of an advertising claim may depend on resolving a dispute over the facts).

The scope of an advertised claim is determined “in its full context.” Southland Sod, 108 F.3d at 1139. Accordingly, a message may be conveyed explicitly or by “necessary implication.” Id. That is, when the message is “necessarily and unavoidably . . . received by the consumer,” Novartis, 290 F.3d at 588, from “the words or images” of the advertisement “considered in context,” Time Warner Cable, Inc. v. DIRECTV, Inc., 497 F.3d 144, 158 (2d Cir. 2007). 

“A claim is conveyed by necessary implication when, considering the advertisement in its entirety, the audience would recognize the claim as readily as if it had been explicitly stated.” Clorox, 228 F.3d at 35.

The Ninth Circuit recently affirmed a preliminary injunction against advertisements about the horsepower of garbage disposals because the advertisements did not reflect the output power of the disposals' motor, even though they did accurately reflect the electrical power drawn by its units. InSinkErator, LLC v. Joneca Co., No. 25-286, 2025 WL 3751867, __ F4th __ (9th Cir. Dec. 29, 2025). Joneca had advertised that its garbage disposals are rated at 1/2, 3/4, 1, and 1 1/4 horsepower on its product packaging. 

Horsepower is a unit of power. InSinkErator argued that consumers understand references to “horsepower” to mean “output horsepower”—the amount of power that the motor can provide to the disposal's grinder—rather than to “input horsepower,” the electric power used by the disposal system as a whole. InSinkErator's testing results showed that none of Joneca's products produced the claimed horsepower (for example, Joneca's products were approximately 39% below the claimed 1 1/4 horsepower disposal, and 24% below the claimed 1 horsepower disposal). 

Joneca, on the other hand, argued that its input-horsepower designated garbage disposals tend to match the same output-horsepower advertised by InSinkErator on its disposals, but at a cheaper price, because of various mechanical advantages, like its use of direct current and the torque of its smaller grinder turntable. Thus, Joneca argued that its horsepower claims, based on input to the device as a whole rather than the output available to the grinding mechanism, were not false.

The key question was whether the meaning of “horsepower” in Joneca's advertising was unambiguous. 

The evidence in the record included a national retailer's website that described horsepower for a disposal unit as “[t]he total power output capability from the included motor.” 

On the other hand, Underwriters Laboratories standard UL 430 used input power for rating disposal units. 

The Ninth Circuit held that it was not clear error for the district court to have found that Joneca's horsepower claims referred to “output” horsepower by necessary implication where there were “battling expert opinions” relying on a wide range of supporting resources, including industry resources and a national retailer's website. 

As explained by the websites of national retailers, “Garbage disposal horsepower (HP) determines what the disposal is capable of grinding” and “Food waste will be ground into finer particles [by disposals with higher horsepower].”

The UL guideline, on the other hand, was a non-consumer-facing safety standard that was “plainly a safety guide for ensuring that switches and controls can safely handle the input current drawn by a motor” which provided for current input testing “regardless” of horsepower designations on the motor or accompanying packaging. There also was correspondence from UL engineers that “UL 430 is a safety standard for Waste Disposers and is not meant to be used to determine the horsepower ratings of Waste Disposers” (while potentially hearsay, it was nonetheless appropriate to consider for a preliminary injunction, see Johnson v. Couturier, 572 F.3d 1067, 1083 (9th Cir. 2009) (“A district court may, . . . consider hearsay in deciding whether to issue a preliminary injunction”); see also Flynt Distrib. Co. v. Harvey, 734 F.2d 1389, 1394 (9th Cir. 1984) (“The trial court may give even inadmissible evidence some weight, when to do so serves the purpose of preventing irreparable harm before trial.”)). 

The Ninth Circuit held that: 

At least when literal falsity is shown by evidence, a complete lack of substantiation for the opposing position—or absence of “conflicting evidence,” as Joneca puts it—is not required. In Southland Sod, this court explained that claims supported by product testing might nonetheless be literally false if the tests were “‘not sufficiently reliable to permit one to conclude with reasonable certainty that they established' the claim made.” 108 F.3d at 1139 (quoting McNeil-P.C.C., Inc. v. Bristol-Myers Squibb Co., 938 F.2d 1544, 1549 (2d Cir. 1991)). The court anticipated that this unreliability could be shown by contradiction or by lack of support from “other scientific tests,” id.—in Joneca's words, “conflicting evidence.”

With respect to materiality, “direct evidence showing how consumers would likely react to the alleged deception”—“like surveys and consumer declarations”—may show that a deception is material; but the baseline proposition is that “[c]ircumstantial evidence is not only sufficient, but may also be more certain, satisfying and persuasive than direct evidence.” Mi Familia Vota v. Fontes, 129 F.4th 691, 724 (9th Cir. 2025) (quoting Desert Palace, Inc. v. Costa, 539 U.S. 90, 100 (2003)). Furthermore, a consumer declaration also may be used to prove materiality. Skydive Ariz., Inc. v. Quattrocchi, 673 F.3d 1105, 1111 (9th Cir. 2012) (“Although a consumer survey could also have proven materiality in this case, we decline to hold that it was the only way to prove materiality.”). 

The Ninth Circuit affirmed that the district court found that InSinkErator was likely to “show that the false advertising was material.” 

This conclusion was supported not only by the general importance of horsepower to consumers, but also by a lengthy analysis of the use of horsepower as a “key differentiating factor when it comes to purchasing and advertising garbage disposals” (emphasis added), with national retailers organizing products by horsepower designation. For example, the district court explained, Home Depot displays competitors' disposals side-by-side based on their horsepower labels, i.e., “Joneca's 1HP disposal [is] adjacent to InSinkErator's 1HP disposal.” Home Depot describes 1 horsepower disposals as “Heavy Duty,” 3/4 horsepower disposals as “Medium Duty,” and 1/3 and 1/2 horsepower disposals as “Light Duty.” Because retailers display disposals to consumers by horsepower level, it was reasonable for the district court to infer that a false claim about a disposal's horsepower—i.e., a horsepower claim that causes a disposal that lacks even the horsepower to qualify as Medium Duty to be displayed in the Heavy Duty section—would materially affect whether and how consumers would compare the unit to competing products.

Thus, the fact that retailers organized disposals by horsepower “signals that horsepower is an important—if not primary—distinction used by retailers to market [disposals] to consumers.” 

The Ninth Circuit also held that the district court did not err in relying on InSinkErator's “market research” showing that “consumers ranked horsepower as one of the top purchasing considerations for garbage disposals.” 

With respect to injury under the Lanham Act injury, the Ninth Circuit noted with approval the helpful guidance from the Second Circuit decision in Church & Dwight Co. v. SPD Swiss Precision Diagnostics, GmBH, 843 F.3d 48, 70–71 (2d Cir. 2016) that “in many cases the evidence and the findings by the court that a plaintiff has been injured or is likely to suffer injury will satisfy the materiality standard—especially where the defendant and plaintiff are competitors in the same market and the falsity of the defendant's advertising is likely to lead consumers to prefer the defendant's product over the plaintiff's.” 

Thus, the district court did not err in finding that, when “a false statement is prominently displayed on a direct competitor's product, and sold side-by-side at the same retailer as if to compare products and value, there is a real likelihood” of “diverted sales or diminished goodwill.” 

In affirming the preliminary injunction, the Ninth Circuit held that the district court did not err in finding that InSinkErator would be irreparably harmed absent preliminary relief, in balancing the hardships, and in finding that the injunction was in the public interest.