The biggest lawsuits in history include the $206 billion Tobacco Master Settlement Agreement, opioid litigation that has collectively surpassed $50 billion, and Supreme Court decisions that reshaped American constitutional rights. No single case wins the title, because “biggest” depends on what you measure: the dollar figure, the number of people harmed, or the lasting effect on the law. A handful of cases score high on all three.
The Largest Dollar Settlements
The Tobacco Master Settlement Agreement of 1998 remains the largest civil settlement in U.S. history. Seven major tobacco companies agreed to pay an estimated $206 billion to 46 states, the District of Columbia, and five U.S. territories, with annual payments continuing as long as cigarettes are sold in the United States.1California Department of Justice. Master Settlement Agreement The money compensated states for healthcare costs tied to smoking-related illness, and the agreement itself banned tobacco advertising aimed at minors.
The 2010 BP Deepwater Horizon oil spill produced the largest environmental damage settlement ever recorded. A federal judge approved the $20.8 billion deal in 2016, resolving civil and criminal claims against BP and its partners under the Clean Water Act and Oil Pollution Act, along with economic damage claims from five Gulf states.2National Oceanic and Atmospheric Administration. Deepwater Horizon Oil Spill Settlements The explosion killed 11 workers and released millions of barrels of oil into the Gulf of Mexico over 87 days.
Volkswagen agreed to spend up to $14.7 billion in 2016 to resolve allegations that it programmed roughly 590,000 diesel vehicles to cheat on emissions tests.3U.S. Department of Justice. Volkswagen to Spend Up to $14.7 Billion to Settle Allegations of Cheating Emissions Tests The software detected when a car was being tested and temporarily reduced emissions, while producing far higher pollution during normal driving. The settlement covered buybacks, environmental remediation, and consumer compensation.
Mass Torts That Affected Millions
Mass tort cases let thousands or millions of people harmed by the same product pursue claims together. Individual awards may be modest, but the cumulative payouts dwarf most conventional lawsuits.
Opioid Litigation
The opioid epidemic has generated what may become the largest mass tort in American history. Manufacturers, distributors, and pharmacies have collectively agreed to pay well over $50 billion to states, cities, and tribes for their roles in a crisis that has killed more than half a million Americans since 1999. Purdue Pharma, the maker of OxyContin, filed a reorganization plan providing more than $7.4 billion in distributions to creditors, funded in part by the Sackler family that owned the company.4Purdue Pharma. Purdue Pharma LP Files New Plan of Reorganization The three largest drug distributors agreed to pay roughly $21 billion, and pharmacy chains including CVS, Walgreens, and Walmart agreed to billions more. The money is earmarked for addiction treatment, prevention, and recovery services.
Asbestos
Asbestos litigation has been moving through the courts since the 1980s and shows no sign of ending. More than 60 active trust funds hold over $30 billion to compensate workers and family members who developed mesothelioma, lung cancer, and other diseases from exposure. Because asbestos-related cancers can take decades to appear, new claims continue to be filed. Many responsible manufacturers went bankrupt and established these trust funds as part of their reorganization plans, creating a compensation system that runs alongside ongoing lawsuits against solvent companies.
PFAS “Forever Chemicals”
A newer mass tort involves PFAS, synthetic chemicals nicknamed “forever chemicals” because they do not break down in the environment. In 2024, 3M agreed to pay up to $10.3 billion in present value, with a nominal cap of $12.5 billion, over 13 years to public water systems that detected PFAS contamination.53M. 3M Settlement With Public Water Suppliers to Address PFAS Other chemical manufacturers face similar litigation. PFAS contamination has been linked to cancer, thyroid disease, and immune system problems, and the chemicals have been detected in drinking water supplies across the country.
Agent Orange and Fen-Phen
Two earlier cases helped establish the mass tort model. The Agent Orange litigation, filed in 1979 on behalf of roughly 250,000 Vietnam War veterans, produced a $180 million settlement in 1984 for health problems linked to the herbicide used as a defoliant during the war. It was one of the first cases to show that large groups exposed to the same toxic substance could band together in a single lawsuit. The Fen-Phen diet drug litigation followed. After the appetite-suppressing drug combination was linked to potentially fatal heart valve damage, the manufacturer agreed to a $3.75 billion settlement, at the time the largest pharmaceutical settlement in U.S. history.6ABC News. Judge OKs $3.75 Billion Fen-Phen Payment
Government Enforcement That Reshaped Industries
When federal or state agencies bring lawsuits, the stakes go beyond money. These actions can restructure entire industries and force lasting changes in how companies operate.
Financial Crisis Bank Settlements
The 2008 financial crisis triggered a wave of enforcement against major banks. Bank of America paid $16.65 billion to settle allegations that it sold billions of dollars in risky mortgage-backed securities while hiding the true quality of the underlying loans.7Securities and Exchange Commission. Bank of America Admits Disclosure Failures to Settle SEC Charges JPMorgan Chase agreed to a $13 billion settlement for similar conduct, including $9 billion in cash penalties and $4 billion in borrower relief.8JPMorgan Chase. JPMorgan Chase Reaches Settlement Both banks admitted to specific fraudulent practices as part of the deals.
Recent Environmental and Banking Penalties
In 2024, engine manufacturer Cummins agreed to pay a $1.675 billion penalty for programming diesel engines with software that reduced or deactivated emissions controls during normal driving. It was the largest civil penalty ever assessed under the Clean Air Act and the second-largest environmental penalty in history.9U.S. Environmental Protection Agency. 2024 Cummins Inc Vehicle Emission Control Violations Settlement The same year, TD Bank faced over $3 billion in combined penalties for Bank Secrecy Act violations. The Treasury Department’s Financial Crimes Enforcement Network assessed a record $1.3 billion penalty against the bank,10Financial Crimes Enforcement Network. FinCEN Assesses Record $1.3 Billion Penalty Against TD Bank and the Department of Justice secured an additional $1.8 billion through a criminal plea agreement.11United States Department of Justice. United States of America v TD Bank NA
Antitrust, Then and Now
Government antitrust power has produced some of the most structurally significant lawsuits ever, even when no fine was involved. In 1911, the Supreme Court found that Standard Oil’s dominance over the petroleum industry constituted an unreasonable restraint of trade and ordered the company broken into more than 30 separate entities.12Justia. Standard Oil Co of New Jersey v United States, 221 US 1 (1911) Seven decades later, the government forced AT&T to divest its local telephone companies in a 1982 consent decree, breaking the “Ma Bell” monopoly into seven regional companies and opening telecommunications to competition.13Federal Judicial Center. The Breakup of Ma Bell – United States v AT&T
The current generation of antitrust enforcement targets Big Tech. In August 2024, a federal court ruled that Google illegally monopolized the markets for general search services and search advertising through exclusive contracts with device makers and browser developers, holding a market share above 89%.14Congressional Research Service. District Court Holds That Google Unlawfully Monopolizes Online Search After a remedies trial in 2025, the court prohibited Google from entering or maintaining exclusive distribution agreements for its search engine, Chrome browser, and AI products, and ordered the company to share search data with competitors.15United States Department of Justice. Department of Justice Wins Significant Remedies Against Google In a separate case, a Virginia federal court found that Google monopolized digital advertising technology markets through acquisitions and anticompetitive auction manipulation over 15 years.16United States Department of Justice. Department of Justice Prevails in Landmark Antitrust Case Against Google The FTC’s antitrust case against Meta, alleging the company used its acquisitions of Instagram and WhatsApp to maintain a monopoly in personal social networking, is on appeal after Meta won at the trial court level in late 2025.17Federal Trade Commission. FTC Appeals Ruling in Meta Monopolization Case
Supreme Court Cases That Rewrote American Law
Some of the biggest lawsuits in history produced no payout at all. They changed how the legal system works and how Americans live, because a single Supreme Court decision can rewrite the rules for the entire country.
Brown v. Board of Education (1954) is the clearest example. The Court held that racial segregation in public schools violated the Equal Protection Clause of the Fourteenth Amendment, reversing the “separate but equal” doctrine that had stood since 1896.18Justia. Brown v Board of Education of Topeka, 347 US 483 (1954) The decision forced 46 states to change their laws and became the legal foundation for the civil rights movement and desegregation efforts that followed.
Miranda v. Arizona (1966) produced what are now the most recognizable words in criminal justice. The Court ruled that statements obtained during police interrogation are inadmissible unless the suspect was first informed of the right to remain silent, that statements could be used against them, and that they had a right to an attorney, including a court-appointed one if they could not afford to hire their own.19Library of Congress. Constitution Annotated – Amdt5.4.7.3 Miranda and Its Aftermath A single case about a kidnapping confession in Phoenix became a procedural requirement in every police station in the country.
Roe v. Wade (1973) recognized a constitutional right to abortion rooted in the Fourteenth Amendment’s protection of personal privacy.20Legal Information Institute. Roe v Wade (1973) For nearly 50 years, it defined the legal boundaries of reproductive rights in America. In 2022, the Court overturned that decision in Dobbs v. Jackson Women’s Health Organization, holding that the Constitution does not confer a right to abortion and returning the question to state legislatures.21Supreme Court of the United States. Dobbs v Jackson Womens Health Organization Both decisions rank among the most consequential the Court has ever issued.
Carpenter v. United States (2018) brought constitutional law into the digital age. The Court held that warrantless government collection of historical cell phone location records is a search under the Fourth Amendment, and that law enforcement generally needs a warrant before compelling a wireless carrier to hand over that data.22Supreme Court of the United States. Carpenter v United States The ruling rejected the argument that people lose their privacy rights in data simply because a third-party company holds it, and its framework continues to shape how courts draw the line between security and privacy as location tracking and digital surveillance expand.