How Are Demographic Groups Defined in Mass Tort Litigation Claims?

By Steve Levine · Updated October 11, 2026

Demographic groups in mass tort litigation are almost never defined by demographics alone. They are defined by objective, checkable facts — where you lived, when you were exposed, what product you bought, what diagnosis appears in your medical records — and age, sex, or race enter only where a statute, a scientific study, or a settlement grid makes them a condition of eligibility.

That distinction matters because it decides who gets paid. A group described as "Black women harmed by hair products" cannot be administered; a group described as women diagnosed with uterine cancer after purchasing a named relaxer brand between specific dates can be. Below is how courts, statutes, and claim administrators actually draw those lines, and what each approach means for an individual claim.

The rule that forces an objective definition
How strictly must the group be delimited?
When a statute defines the group instead of a court
Plaintiff fact sheets reconstruct the cohort one person at a time
Where demographics genuinely are part of the definition
Checking whether you fall inside a definition
Frequently Asked Questions

The rule that forces an objective definition

The textual hook is Federal Rule of Civil Procedure 23(c)(1)(B), which says a certification order "must define the class" and state the class claims, issues, or defenses. That single sentence is why the group definition, rather than the injury, is the gatekeeping step in a class action. The Federal Judicial Center's pocket guide for judges instructs that the definition be "precise, objective, and ascertainable." "Ascertainable" is the operative word. It means a court can tell, by looking at the definition, whether any given person is in or out — without first deciding whether that person wins.

A definition that fails this test is called a "fail-safe" class: membership turns on the merits, so anyone who loses was never a member, and the defendant can never win a binding judgment. Demographic labels are the classic failure mode here. Race, ethnicity, and even gender are self-described categories with contested edges, and no court-supervised administrator can audit them against a record. Exposure, purchase, residence, and diagnosis can all be audited, which is why they do the work that demographics appear to be doing.

How strictly must the group be delimited?

Federal circuits disagree, and the disagreement is practical rather than academic. The Third Circuit requires that a Rule 23(b)(3) damages class be "currently and readily ascertainable based on objective criteria," and demands a "reliable and administratively feasible mechanism" for sorting people into or out of the definition. That standard appears in its precedential opinion in No. 19-2809. Under it, a declaration in which a claimant describes their own demographic characteristics is generally not enough.

The Seventh Circuit went the other way. In Mullins v. Direct Digital, decided July 28, 2015, it held that "nothing in Rule 23 mentions or implies a heightened ascertainability requirement," and rejects only definitions that are vague, subjective, or fail-safe. A low-value consumer class with no purchase records can survive there and fail in Philadelphia. For a claimant, the consequence is that the same facts can be a certified class in one courthouse and no class at all in another. Where a case is filed is a strategic choice made by counsel, not a neutral detail.

When a statute defines the group instead of a court

Most mass torts are not class actions. They are individual lawsuits consolidated into multidistrict litigation, and sometimes the eligible group is set by Congress rather than by a certification order. The Camp Lejeune Justice Act is the clearest example: the Department of Veterans Affairs' Camp Lejeune page describes coverage for anyone who lived, worked, or was otherwise exposed at the base for at least 30 days between August 1, 1953 and December 31, 1987, including in utero exposure. Notice what that definition contains and what it omits. There is a place, a minimum duration, a date window, and an explicit extension to the unborn.

There is no reference to race, income, rank, or branch of service. The demographic group is a cohort — everyone who was physically present, long enough, during the contaminated years. The Justice Department then converted that cohort into a payment grid. Its Public Guidance on the Elective Option, issued September 6, 2023, keys awards to exposure duration in three bands — 30 to 364 days, one to five years, and over five years — paying $150,000, $300,000, or $450,000 for Tier 1 cancers and $100,000, $250,000, or $400,000 for Tier 2 conditions, plus $100,000 for death. Diagnosis must have come between two and 35 years after exposure. Duration of presence, not identity, drives the number.

Plaintiff fact sheets reconstruct the cohort one person at a time

In MDLs, individual demographics are collected through a court-ordered Plaintiff Fact Sheet — a standardized questionnaire every claimant must complete under oath. In the AFFF firefighting foam litigation in the District of South Carolina, Case Management Order 5.G requires date of birth, gender, and every residence since 1970 along with the water provider serving each address. That is how an exposure cohort gets rebuilt claimant by claimant. The residence-and-water-utility history converts a vague group ("people who drank contaminated water") into a mapped, verifiable one.

Date of birth and gender are recorded because they affect latency and disease risk, not because they define membership. Two practical warnings follow. First, an incomplete or late fact sheet is a common route to dismissal, and the deadlines are set by court order, not by your lawyer's convenience. Second, the residence history is the hardest part to assemble retroactively — old leases, utility bills, school records, and tax filings are what make it provable.

Where demographics genuinely are part of the definition

Sometimes a demographic boundary is real, because the underlying science found the risk in a specific population. The National Institutes of Health reported on October 17, 2022 that women who used chemical hair straighteners more than four times a year had roughly double the uterine cancer risk — 4.05% versus 1.64% by age 70 — across 33,947 women aged 35 to 74, with 378 cases. About 60% of recent users in that study were self-identified Black women. Filings borrow that boundary, but they borrow it as frequency of product use plus diagnosis, with the demographic pattern as context for causation and damages. The study tells you who was harmed.

The complaint still has to describe who can prove it. The reverse case is equally instructive. A demographic adjustment inside a settlement can itself be unlawful bias. The NFL concussion program's revised rules, approved March 4, 2022, bar the use of race norms or race demographic estimates for Black or white players going forward and require recomputation of earlier dementia scores — a change reported by the Associated Press. Race had been used to set baseline cognitive scores, which systematically reduced Black retirees' measured impairment and their payouts.

Checking whether you fall inside a definition

The scale here is large enough that most people who qualify never file. As of January 5, 2026, the Judicial Panel on Multidistrict Litigation counted 158 MDL dockets holding 197,965 pending actions, led by AFFF products liability with 15,213, proton-pump inhibitors with 11,322, and hair relaxer with 10,948.

The last two are defined largely by patient and consumer subgroups. To test your own position against a definition, work through the elements in the order a claims administrator will: If a program or an advertisement describes eligibility purely in demographic terms — an age bracket, a gender, a racial group — treat that as marketing shorthand and ask for the actual criteria. The enforceable definition will name a product, a place, a date range, and a diagnosis.

**Place and time.** Did you live at, work at, or use the product in the covered location during the covered dates? Pull documents, not memory.
**Duration or frequency.** Camp Lejeune requires 30 days; the hair straightener finding turns on use more than four times a year. Thresholds are hard edges.
**Diagnosis and its date.** Many programs impose a latency window — Camp Lejeune's Elective Option requires diagnosis two to 35 years after exposure.
**Tier.** Where a grid exists, your condition's tier and your exposure band together set the figure, as the three-by-two Camp Lejeune table shows.
**Forum.** In a consumer class without purchase records, whether you have a certifiable class may depend on which circuit hears it.

Frequently Asked Questions

Can I be excluded from a class because my race or ethnicity was not part of the study?

No. Study populations describe where researchers found elevated risk; class definitions and MDL fact sheets turn on product use, exposure, and diagnosis. Being outside a study's demographic majority is not itself a bar to filing.

Does a payment grid mean everyone in my group gets the same amount?

Not usually. Camp Lejeune's Elective Option pays by exposure duration band and disease tier, so two claimants from the same base in the same years can receive $150,000 and $450,000 for Tier 1 cancers depending on how long they were there.

What happens if my residence history has gaps?

Gaps weaken the exposure element rather than eliminating it, but the AFFF fact sheet asks for every address since 1970 with its water provider, so unexplained gaps invite challenge. Reconstruct from leases, utility accounts, employment records, and tax returns.

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