Garmin is facing a proposed class action lawsuit over the Index S2 Smart Scale, with the core allegation being that the company marketed its body composition features as accurate when the underlying technology -- foot-to-foot bioelectrical impedance analysis (BIA) -- cannot support those claims.
The case, Maurer v. Garmin International, Inc. et al (1:26-cv-06389), was filed on May 29, 2026, in the US District Court for the Northern District of Illinois. The plaintiff, Victor Maurer, is seeking monetary damages and a declaration that the Index S2 cannot accurately measure body composition. The complaint is 56 pages, filed as an "Other Fraud" case with a jury demand.
This is a proposed class action, not a ruling. Garmin has not publicly responded to the suit. At this stage, it's an allegation that will work its way through the courts -- and many consumer class actions settle, narrow, or get dismissed before they ever see a courtroom.
That said, the lawsuit raises some points that are worth looking at closely.
What the Lawsuit Claims
The complaint takes issue with Garmin's marketing of the Index S2's body composition features -- specifically body fat percentage, muscle mass, and related metrics. Weight measurement is not in dispute. The lawsuit is about whether those derived body composition numbers are legitimately accurate or whether they're being presented as more precise than the technology allows.
According to the filing, Garmin "failed to disclose to Plaintiff and other Class Members vital information regarding the Smart Scale's inability to accurately measure body composition."
The core technical argument is this: the Index S2 uses foot-to-foot BIA, which sends an electrical current from one foot to the other through bare skin. Because the signal travels only through the lower body, the lawsuit argues it cannot capture whole-body composition. A four-point BIA system that uses both feet and hands would measure more of the body directly and is generally considered more accurate for clinical body composition purposes.
The complaint cites a 2021 study published in JMIR mHealth uHealth that compared three foot-to-foot smart scales against DEXA (dual-energy X-ray absorptiometry), which is the clinical gold standard for body composition measurement. The study found that those smart scales underestimated both fat mass and muscle mass by as much as 8kg, or roughly 8 percentage points, compared to DEXA. Median errors in the same study were smaller -- 2.2 to 4.4kg -- but the lawsuit focuses on the worst-case figures.
The Marketing Language Is the Real Target
What's interesting about this lawsuit is that the science is almost secondary. The legal argument leans heavily on what Garmin said about the product, not just what the technology does.
Garmin's product page uses the phrase "Accuracy matters when it comes to your goals." The lawsuit points to that as an implicit accuracy claim attached to body composition data. An Amazon listing referenced in the complaint is more direct, stating buyers can get "accurate measurements for weight, weight trend, body fat percentage, BMI, skeletal muscle mass, and more."
And then there's the launch statement from Garmin VP of worldwide sales Dan Bartel, which the5krunner flagged as potentially the most damaging line in the case: "The Index S2 builds on the success of the first-generation Garmin smart scale with exceptional accuracy."
Unqualified. In a product announcement that leads with body composition as the headline feature. That's the sentence the plaintiff's lawyers will return to.
What Garmin Will Likely Argue
Garmin has several potential lines of defense, and some of them are reasonable.
First, the JMIR study didn't test a Garmin Index S2. It tested a Tefal scale, a Terraillon scale, and a Withings scale. No Garmin device was in that study. The lawsuit is extrapolating from a class of products to a specific brand, which Garmin's lawyers will absolutely challenge.
Second, the 8kg figure is a worst-case outlier drawn from a clinical population recruited specifically for obesity and chronic illness research -- not a representative sample of everyday users. Median errors in the same study were in the 2.2 to 4.4kg range, which is a meaningfully different number.
Third, Garmin's Owner Manual does caution that hydration and activity levels affect BIA measurements and recommends using the scale under consistent conditions for best results. Whether that disclaimer is prominent enough to matter legally is a different question, but the company can point to it.
Fourth, every major competitor uses the same foot-to-foot two-point BIA method. Withings, Fitbit, Tanita, Eufy -- all of them use the same basic approach. If foot-to-foot BIA is fundamentally flawed as a body composition tool, the lawsuit doesn't explain why Garmin is uniquely responsible for marketing it.
Fifth, the industry-wide position is that BIA smart scales track relative change over time, not absolute clinical values. You step on the scale every morning under the same conditions and watch the trend. That's how these devices are designed to be used, and it's a reasonable framework -- even if the marketing sometimes oversells the precision.
Why Garmin Might Be Vulnerable Anyway
The science might be on Garmin's side, but the marketing language is a liability.
Consumer fraud cases don't require a product to be completely worthless. They look at the overall impression created by marketing and ask whether a reasonable buyer would be misled. "Exceptional accuracy" in a product announcement where body composition is the headline feature, combined with an Amazon listing promising "accurate measurements for body fat percentage," is not a trivially defensible position.
The "everyone else does it too" defense might help Garmin, but it won't eliminate liability on its own. And the specific Dan Bartel quote -- with a named executive making an unqualified accuracy claim at launch -- is the kind of thing that hangs around in discovery.
The lawsuit also seeks a declaration that the Index S2 "cannot accurately measure body composition." That's a stronger remedy than money in some ways -- it would require Garmin to either change its marketing or stop making body composition claims entirely. That kind of injunctive relief is harder to settle away quietly.
What This Means for Index S2 Owners
If you own an Index S2, this lawsuit doesn't change what the scale does. It still measures weight reliably. It still tracks trends over time. The body composition numbers are still estimates, and they've always been estimates -- that's how BIA scales work.
What the lawsuit changes is the question of whether you were told that clearly enough. If Garmin's marketing led you to believe the body fat percentage was a precise measurement rather than an approximation, and if the court agrees that the marketing was misleading, you might be entitled to a refund.
The practical takeaway: don't treat the body composition numbers on any smart scale -- Garmin or otherwise -- as clinical-grade data. Use them to track direction and趋势 over weeks and months. Don't treat a 1% change in body fat as meaningful when the margin of error on the technology is multiple percentage points.
The Bottom Line
This is a case about marketing language as much as it is about technology. The Index S2 is not uniquely inaccurate among smart scales -- foot-to-foot BIA is a known limitation of the entire product category. But Garmin's marketing copy, particularly the "exceptional accuracy" statement from a named executive, is the kind of thing that makes a plaintiff's lawyer's day.
The case is in its early stages. Garmin hasn't responded publicly. Class certification is still ahead, and many proposed class actions never get that far. This is worth watching, but it's not a verdict.
What it does do is raise a legitimate question that anyone buying a smart scale should ask: what kind of accuracy are you actually getting, and is the marketing being honest about the limitations?
This article is based on publicly available court filings, the Singletracks report, the5krunner analysis, and GadgetsAndWearables coverage. We will follow this case as it develops.