Mass tort and class action are two distinct legal processes that people often confuse. Both involve groups of plaintiffs harmed by the same defendant and/or product. The difference, however, lies in:
The simplest way to understand the distinction: if you suffered a serious personal injury with specific causation and damages unique to your situation (e.g. pre-existing conditions, other potential causes of the injury, different injuries, medical bills, lost income, pain and suffering), your case likely falls under mass tort litigation, where each plaintiff’s claim is evaluated individually. If you suffered a shared economic loss (you overpaid for a product, were deceived by false advertising, or lost value due to a defect), your case may proceed as a class action, where damages are distributed across the group.
The attorneys at Wisner Baum have obtained over $4 billion on behalf of clients across a broad range of practice areas, including mass tort and class action litigation. In this blog, we explain how each type of case works, provide real examples, and help you understand which may apply to your situation.
A mass tort lawsuit involves a large number of plaintiffs who were each injured by the same product or event, but whose injuries differ in type or severity. Unlike a class action, each plaintiff maintains an individual claim. This matters because it means your case is evaluated on its own merits, including the strength of your case, possible other causes of your injuries, and your specific damages (the surgeries you needed, the wages you lost, the ways your life was affected, for example) rather than lumped in with everyone else’s.
When enough individual lawsuits raise similar factual questions, a motion can be filed with the Judicial Panel on Multidistrict Litigation (JPML) to consolidate them into a multidistrict litigation (MDL). Consolidation streamlines the pretrial process—discovery, expert testimony, and procedural motions are handled once rather than repeated in every individual case—but each plaintiff’s claim remains separate. Cases may resolve through negotiated settlements, jury verdicts at trial, or dismissal.
Toxic Baby Food: Wisner Baum represents over 8,000 families alleging that baby food contaminated with heavy metals contributed to autism, ADHD, and other neurodevelopmental disorders in children. Managing Partner R. Brent Wisner was appointed co-lead trial counsel in the toxic baby food MDL.
Antipsychotics: Wisner Baum represents hundreds of women and men alleging that certain antipsychotic medications, including Risperdal, Invega, and Zyprexa, may increase the risk of breast cancer. Ongoing lawsuits allege that manufacturers failed to warn about the potential risk.
Roundup (Glyphosate): Wisner Baum played a central role in litigation against the maker of Roundup, helping to secure billions of dollars on behalf of individuals who developed cancer after long-term exposure to glyphosate. The firm won landmark jury verdicts and helped negotiate nearly $11 billion in settlements nationwide.
Spinal Cord Stimulators: Lawsuits allege that certain spinal cord stimulator devices caused debilitating complications—including chronic pain, nerve damage, and lead migration—rather than providing the pain relief they were marketed to deliver.
Port Catheters: Patients allege implanted port catheter devices from Bard and ICU Medical fractured, migrated, and/or caused life-threatening complications. Wisner Baum is actively pursuing claims on behalf of affected patients.
Atrazine: The International Agency for Research on Cancer (IARC) linked atrazine to an increased risk of non-Hodgkin lymphoma. Wisner Baum represents farmworkers and others alleging long-term atrazine exposure contributed to their cancer diagnoses.
Paraquat: Lawsuits allege that chronic exposure to the herbicide paraquat is linked to an increased risk of Parkinson’s disease. Wisner Baum represents agricultural workers and others who were exposed to this chemical.
In a class action lawsuit, individual claims are consolidated into a single case. A court must first certify the class by determining that the plaintiffs share common legal and factual questions, that the claims are typical of the group, and that a class action is the most efficient way to resolve them. Without certification, the class action cannot proceed.
Once certified, a lead plaintiff (sometimes called the class representative) serves as the named party whose claims are typical of the group. Class counsel handles litigation strategy and settlement negotiations on behalf of the entire class, subject to court approval. The case proceeds as one lawsuit. Members of the class are notified and allowed to opt out if they prefer to pursue their own claims independently. Those who remain are bound by the outcome, good or bad.
Class actions are common in cases involving consumer fraud, false advertising, overcharging, or defective products where the financial harm is broadly similar across plaintiffs.
Actos RICO Class Action: This class action alleges that Takeda Pharmaceutical Company and Eli Lilly conspired to conceal the bladder cancer risk associated with the diabetes drug Actos to protect sales. The class represents third-party payers who covered Actos prescriptions during the concealment period. Class certification was granted in 2023 and affirmed by the Ninth Circuit in 2025, making it the first non-settlement national RICO class action ever certified against a major pharmaceutical company.
Dexcom Class Action: A class action has been filed against Dexcom alleging that its G6/G7 devices and sensors provide faulty readings. The case is still in its initial stages, and no lead plaintiffs have been appointed, nor has a class been certified.
The differences between these two types of litigation come down to individuality, control, and compensation.
In a mass tort, each plaintiff retains their own claim and their own attorney. Their damages are assessed individually, which means two plaintiffs in the same litigation may receive very different settlement amounts depending on the strength of their case, the severity of their injuries and the impact on their daily lives, among other things. A mass tort may be consolidated into an MDL for pretrial efficiency, but the claims never merge into one single case.
In a class action, claims are consolidated into one lawsuit. A lead plaintiff represents the group (referred to as a class representative), and most class members have limited involvement in day-to-day litigation decisions. Settlement funds are typically distributed across the class, often through a formula that may account for individual documented losses. Class action settlements generally result in smaller per-person payouts than mass tort settlements because they are limited to economic losses. A class member who wants more control over their case, however, can still opt out and pursue an individual claim with their own attorney.
Settlement structure is one of the most important differences between these two types of litigation.
In mass tort cases, settlements are typically structured around a tiered or point-based system. Plaintiffs may be assigned to tiers based on factors like diagnosis, severity of injury, other possible causes of the injury, duration of exposure, and impact on quality of life. A plaintiff with a more severe injury and/or a stronger causal link may generally be placed in a higher tier and receive a larger settlement. The individual case evaluations are usually done by an independent “special master” who is appointed by the Court to create the tiers/points system and to evaluate each case. This process takes significantly longer, but it ensures that compensation reflects individual harm.
In class action cases, settlement funds are distributed across the entire class. Some class actions divide funds equally; others use a pro rata formula based on documented purchases or losses. Because the pool is shared, only reflects economic losses, and the class can include thousands or even millions of members, per-person payouts in class actions tend to be significantly smaller. However, class actions can be the most efficient path to recovery when individual damages are modest and uniform.
This brings us to an important question clients often have: Is my case a class action or part of a mass tort?
The type of harm you suffered is the strongest indicator of which legal path your case will follow. If you suffered a serious physical injury (a cancer diagnosis after chemical exposure or complications from a medical device), your case will likely be part of a mass tort. The cause of and type of injuries vary dramatically from person to person, so recoveries will vary in accordance with specific medical records, medical costs, lost income, pain, and the ways a claimant’s life has been affected. That individual evaluation is what mass tort litigation is designed for.
If you suffered an economic loss that was broadly shared with other consumers (you bought a product that was falsely advertised or paid for a drug that didn’t work as claimed), your case may proceed as a class action. The shared nature of the financial harm makes it efficient to resolve these claims as a group.
Some situations involve both. A defective product might cause physical injury to some users (mass tort) and economic loss to others who purchased it but weren't harmed (class action). For example, Wisner Baum litigated Roundup on both fronts. Our attorneys represented individuals diagnosed with cancer after glyphosate exposure in mass tort cases, while also pursuing a class action against Monsanto over false advertising claims that the product was safe. The same product gave rise to two fundamentally different types of litigation, each serving a different group of people harmed in different ways.
An attorney experienced in both types of litigation can evaluate your circumstances and advise on the best path forward.
If you believe you have been harmed by a dangerous product, toxic exposure, or defective medical device, the attorneys at Wisner Baum can help you understand your legal options. Attorneys at the firm have been appointed to leadership and steering committees on some of the largest mass tort and class action cases in the country and have secured substantial recoveries for clients in these cases.
Contact us today to schedule a free case evaluation. It is important to act promptly, as statutes of limitations restrict the amount of time you have to file a claim.
"Wisner Baum gave exceptional attention to all aspects of the case, detailed inquiry, and tenacious overview of all the information submitted. The paralegals are efficient and diligent. I was completely surprised to find an empathic personal message to take care of my own health during the challenging time of being a full-time caretaker.*"
In May of 2019, the jury in the case of Pilliod et al. v, Monsanto Company ordered the agrochemical giant to pay $2.055 billion in damages to the plaintiffs, Alva and Alberta Pilliod, a Bay Area couple in their 70s. R. Brent Wisner served as co-lead trial attorney for the Pilliods, delivering the opening and closing statements and cross-examining several of Monsanto’s experts. Wisner Baum managing shareholder, Michael Baum and attorney Pedram Esfandiary also served on the trial team in the Pilliod case.
The judge later reduced their award to $87M. Monsanto appealed the Pilliod’s verdict which the California Court of Appeal for the First Appellate District denied on August 9, 2021. Monsanto then requested the California Supreme Court review the appeal’s court decision, which the court denied on Nov. 17, 2021. Monsanto (Bayer) then submitted a petition for a writ of certiorari with the U.S. Supreme Court which SCOTUS denied on June 27, 2022, allowing the final judgment of $87M to remain intact.
$289.2 million jury verdict in Monsanto Roundup trial
Wisner Baum co-represented Dewayne “Lee” Johnson in the first Roundup cancer lawsuit to proceed to trial. On Aug. 10, 2018, a San Francisco jury ordered Monsanto to pay $39.25 million in compensatory damages and $250 million in punitive damages to Mr. Johnson, a former groundskeeper who alleged exposure to Monsanto’s herbicides caused him to develop terminal non-Hodgkin lymphoma.
Months after the jury verdict, the judge overseeing the trial reduced the punitive damages to $39.25 million. Mr. Johnson decided to accept the remittitur, bringing the adjusted amount awarded to Mr. Johnson $78.5 million.
Monsanto (Bayer) appealed the verdict and Johnson cross appealed. On July 20, 2020, the First Circuit Court of Appeals upheld the verdict against Monsanto but reduced Mr. Johnson’s award to $20.5 million. The company chose not to take the case to the U.S. Supreme Court, ending the litigation.
In 2016, Wisner Baum attorney Timothy A. Loranger and six other attorneys in the Plaintiffs’ Management Committee were able to secure a $265 million settlement for victims of the 2015 Amtrak 188 derailment in Philadelphia, one of the largest in the U.S. for 2016.
Not simultaneously, but related litigation sometimes includes both. For example, a defective drug may generate mass tort claims for people who suffered physical injuries and a separate class action for consumers without physical injuries solely seeking refunds. The same product can give rise to both types of litigation depending on the nature of the harm.
Yes. After a class is certified, members are notified and given a window to opt out. If you opt out, you give up your share of any class settlement but retain the right to file an individual lawsuit. This may make sense if your damages are significantly greater than what the class settlement would provide. Talk to an attorney if you are unsure which is the correct path for your claim.
Timelines vary widely. Class actions may resolve more quickly because the claims are consolidated into a single proceeding. Mass tort cases tend to take longer because individual claims require separate evaluation, but this process also tends to produce settlements more closely tailored to each plaintiff’s actual damages.
This depends on your case, but common evidence includes medical records, proof of purchase or use, documentation of expenses related to the harm, and any communications with the manufacturer or provider. An attorney can advise you on what specific documentation will strengthen your claim.
Generally speaking, costs, attorney fees, and any liens on the case (such as medical liens or government reimbursement claims) are deducted from the settlement by the settlement administrator, and the remaining funds are distributed to plaintiffs. In mass tort cases, these deductions are calculated on each individual claim, and attorneys’ fees and costs are based upon your individual retainer agreement with your law firm. In class actions, they are deducted from the total settlement fund before distribution to the class and attorneys’ fees and costs are determined by the Court.
