3M Combat Arms Earplug Litigation: What the $6 Billion Settlement Means for Employers

In August 2023, 3M Company agreed to pay $6.01 billion to resolve claims from approximately 260,000 military veterans and service members who alleged that the company’s Combat Arms Earplugs Version 2 (CAEv2) caused hearing loss and tinnitus. The settlement resolved what had become the largest mass tort in U.S. history by plaintiff count — more than 230,000 individual federal lawsuits consolidated in a multidistrict litigation in the Northern District of Florida. The product at the center of the case was the standard-issue hearing protection device for U.S. military personnel from approximately 2003 to 2015. The allegations were straightforward: 3M knew the earplugs were defective, knew they could loosen imperceptibly during use and provide inadequate attenuation, failed to disclose this to the military, and supplied a hearing protection device to millions of service members that did not perform as labeled. The 3M case is not just a military procurement story. For any employer whose hearing conservation program relies on labeled NRR values without independent verification of real-world performance, the case is an object lesson in what the gap between NRR testing and actual use can cost.

Soundtrace audiometric programs document individual HPD attenuation through fit testing, creating defensible records that the hearing protection provided to each worker was verified to perform adequately.

What the Combat Arms Earplug Was and What Failed

The 3M Combat Arms Earplug Version 2 (CAEv2) was a dual-ended earplug with two different NRR ratings depending on which end was inserted: one end was designed for continuous high-level noise (fully inserted, standard attenuation); the other end was designed for a lower-attenuation, “open” configuration that allowed the wearer to hear voice communications while maintaining some impulse noise protection. This dual-mode design was a legitimate military requirement — soldiers in combat need to hear spoken commands while also protecting against weapons fire and explosions.

The product was sold exclusively to the U.S. military beginning in 1999 and became standard issue. Aearo Technologies, which 3M acquired in 2008, originally developed the product. By the time 3M settled the litigation, the CAEv2 had been issued to millions of service members across Iraq, Afghanistan, and other deployments.

The alleged defect: the CAEv2 was too short. Its shorter-than-standard stem meant that for users with certain ear canal geometries, the earplug would not seat deeply enough to maintain a proper acoustic seal. During insertion, the flanges could fold back slightly and imperceptibly loosen, allowing sound to bypass the seal and enter the canal at levels far higher than the NRR indicated. The user would have no awareness that the fit had failed — the earplug would feel secure while providing dramatically reduced attenuation.

The False Claims Act Case: How It Started

The litigation began not with individual veterans but with a corporate whistleblower. Moldex-Metric, a competing HPD manufacturer, filed a qui tam action under the False Claims Act in 2016, alleging that 3M (through its predecessor Aearo Technologies) had defrauded the U.S. government by knowingly selling defective earplugs. The qui tam complaint alleged that internal Aearo testing had identified the loosening problem as early as 2000 — before the military contract was fulfilled — and that Aearo had developed a folding-over technique to make the earplug seat properly that was not disclosed to the military or included in standard user instructions.

The Department of Justice declined to intervene in the case. Moldex-Metric pursued it independently. In 2018, 3M agreed to pay $9.1 million to the U.S. government to settle the False Claims Act allegations without admitting liability. That settlement attracted significant attention among veterans’ attorneys and the mass tort bar, and within months, thousands of individual civil lawsuits began to be filed.

The MDL and Trial Verdicts Before Settlement

Cases were consolidated into MDL No. 2885 in the Northern District of Florida under Judge M. Casey Rodgers. The MDL grew to become the largest multidistrict litigation in U.S. history, with over 230,000 individual plaintiff cases. Beginning in 2021, the court conducted bellwether trials to test plaintiff and defense theories in front of juries.

Results were mixed. Plaintiffs won several significant verdicts, including awards of $8.2 million, $13 million, and others in the tens of millions range. Defense verdicts also occurred. The mixed results created settlement pressure from both sides: plaintiffs facing uncertain individual outcomes and 3M facing an open-ended stream of trials. 3M’s 2022 attempt to limit its exposure by putting its Aearo subsidiary into bankruptcy — and seeking to stay the MDL under bankruptcy protection — was rejected by federal courts, which found that the bankruptcy was a bad-faith attempt to avoid litigation obligations of a solvent parent company.

The $6.01 Billion Settlement

In August 2023, 3M agreed to pay $6.01 billion to resolve the litigation. The settlement was structured as a payment plan running from 2023 through 2029, with approximately $1 billion paid at signing and the remainder in scheduled tranches. Individual claimant payouts vary widely based on the severity of hearing loss or tinnitus, the claimant’s service history, and participation in specific service branches and deployments. The settlement resolved the overwhelming majority of the MDL, though some holdout plaintiffs continued individual litigation.

No admission of liability was made. 3M maintained that the CAEv2 performed as designed and that any hearing loss suffered by claimants resulted from other causes or improper use. The settlement amount nonetheless represents the second-largest mass tort settlement in U.S. history.

The Technical Failure: Why the Earplug Could Loosen

The technical core of the plaintiffs’ case was the claim that the CAEv2 stem was too short for some users, causing the earplug’s flanges to fold back against the tragus (the cartilage projecting in front of the ear canal) during insertion. When the flanges folded, they could create an apparent acoustic seal that would then loosen during movement or simply over time, allowing an acoustic pathway around the plug that the wearer could not detect by feel or sound.

The alleged internal Aearo remedy was a “folding” technique: an inserter would fold back the opposite end’s flanges during insertion to prevent the near-end flanges from catching. This technique was purportedly documented in internal testing notes but was not included in the standard user instructions issued with the product. Without this technique, users were allegedly more likely to experience the flange-folding problem and the resulting acoustic seal failure.

Plaintiffs argued that Aearo knew this was a problem, knew the remedy, and chose not to include the remedy in user instructions in order to preserve the contract with the military — which specified a certain earplug length. The shorter stem was allegedly a design choice to meet a military size specification, not a manufacturing error.

The NRR Problem the Case Exposed

The 3M case is the highest-profile demonstration of a problem that audiologists, occupational health researchers, and NIOSH have documented for decades: the NRR, as measured under ANSI S3.19 laboratory conditions, consistently overestimates the attenuation achieved by real workers in real workplaces. The EPA-required NRR label is derived from laboratory testing with trained subjects inserting HPDs under expert supervision. Real-world attenuation for the same product in workplace use consistently measures 40–70% below the laboratory NRR.

In the CAEv2 case, the alleged failure was more extreme than simple laboratory-to-field attenuation degradation — it was a specific design feature (stem length) that created a defect mode in which the earplug could fail entirely, providing near-zero attenuation, without the user knowing. But the underlying vulnerability — that users cannot verify their own HPD attenuation without measurement — applies to every earplug in every program that relies solely on NRR for protection adequacy assessment.

Employer Implications: What This Means for Your HPD Program

The 3M case is a manufacturer product liability case, not an employer liability case. The litigation targeted 3M, not the military. But the case creates several clear implications for civilian employer HPD programs:

• Reliance on NRR alone is documented to be inadequate: The gap between NRR and real-world attenuation is now a matter of public judicial record in the world’s largest mass tort proceeding. An employer who provides an HPD with an NRR adequate on paper but fails to verify that workers actually achieve that attenuation has a documented protection gap that is now well-established in legal and scientific literature.
• HPD selection should include verification of fit: Fit testing documents that the employer did not merely provide an HPD — it verified that the HPD provided to each specific worker achieved adequate attenuation for that worker. This is the strongest possible defense against the claim that the HPD program was inadequate.
• Training on correct insertion matters and must be documented: The 3M case turned in part on whether adequate use instructions were provided. An employer who documents fitting training for each worker with each HPD type they use has a much stronger position than one who provides HPDs without documented fitting instruction.
• Worker compensation for NIHL is primarily WC, not tort: In the civilian context, workers injured by occupational NIHL typically pursue WC claims against the employer, not product liability claims against the HPD manufacturer. But the employer’s choice of a defective or inadequate HPD could be raised as a defense argument in a WC apportionment dispute or third-party liability context.

Fit Testing as Documentation and Defense

The most direct lesson the 3M case offers for civilian employer HPD programs is the value of fit testing. Objective HPD fit testing — using systems like the 3M E-A-Rfit, Howard Leight Clarity, or similar MIRE-based systems — generates a per-worker, per-device attenuation measurement documented with a date and device serial number. This record demonstrates:

• The employer did not simply provide an HPD; it verified the HPD worked for each individual worker
• The attenuation at the time of testing was documented and adequate for the worker’s noise exposure level
• The worker was instructed in correct fitting to a degree sufficient to achieve measurable attenuation
• If a worker develops NIHL, the employer can demonstrate that the HPD was verified adequate at regular intervals

The DoD already mandates fit testing under DoDI 6055.12. The CAEv2 problem — a fitting failure mode that was not detectable by feel — would have been identified and documented if systematic fit testing had been part of the program. Workers whose fit tests showed inadequate attenuation would have been refitted or given different HPDs. The 3M litigation is, in part, an argument for why the DoD fit-testing mandate that came after the CAEv2 era should be adopted in civilian programs.

The Product Liability Framework for HPD Failures

The 3M case illustrates the three product liability theories that can be applied to defective HPDs:

• Design defect: The product was designed in a way that made it unreasonably dangerous — here, the stem-length design that created the loosening failure mode. This is the core CAEv2 theory.
• Manufacturing defect: A specific unit deviates from the design in a way that makes it dangerous. Less relevant in the 3M case (the alleged defect was in the design itself, not manufacturing variation).
• Failure to warn: The manufacturer knew of a dangerous characteristic of the product and failed to adequately warn users. Here, the alleged failure to disclose the loosening problem or provide adequate fitting instructions to prevent it.

For civilian employers, these theories apply through the WC contribution framework: if a worker’s hearing loss resulted from a defective HPD provided by the employer, the employer’s indemnification rights against the manufacturer may be available — but only if the employer can document that it provided the HPD and the worker used it as instructed. Without that documentation, the employer may bear the full WC cost without recourse to the manufacturer.

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