Concurrent tortfeasors are two or more parties whose separate, independent acts combine to cause a single injury, and how they split the bill depends on two variables in the jurisdiction where the case is filed: whether the state uses joint and several liability, several-only liability, or a hybrid, and whether it measures each party’s fault under a pure or modified comparative negligence rule. Get those two variables right and the rest of the analysis follows. Get them wrong and a plaintiff can walk away with a fraction of what they expected, or a lightly-at-fault defendant can end up paying the entire judgment.
What Puts Someone in This Category
The label applies when multiple parties each do something wrongful on their own, and those independent acts converge into one harm. Two drivers who both run red lights and collide are the textbook example. A surgeon and an anesthesiologist who each make separate errors during the same operation fit the same pattern. The parties may not know each other exists. What matters is that each one’s conduct was a legal cause of the same indivisible injury.
This is different from acting in concert, where the parties plan or coordinate the wrongful conduct together. Concert liability makes each participant liable for the entire result by design. Concurrent liability arrives at a similar place in some jurisdictions, but through a different route, and with different escape hatches.
Joint and Several Liability, or Only Several
Under joint and several liability, a plaintiff can collect the full amount of damages from any single defendant, no matter how small that defendant’s fault share. A jury finding Defendant A 20% at fault and Defendant B 80% at fault does not stop the plaintiff from collecting 100% from A alone. A then has to chase B for reimbursement.
The rule protects injured people from the risk that one defendant is bankrupt or uninsured. It can also stick a marginally-at-fault defendant with the entire loss, which is why most states have moved away from applying it across the board.
Only about seven states still use pure joint and several liability for everything. Roughly 29 use a modified version, and around 14 have shifted to pure several liability, where each defendant pays their assigned percentage and nothing more. The modifications take different shapes. Some states apply joint and several liability only above a fault threshold like 50% or 51%. Others split by damage type, keeping joint and several liability for economic losses like medical bills and lost wages but limiting defendants to several liability for pain and suffering.
The practical consequences are large. In a pure several state, if one defendant is judgment-proof, the plaintiff simply loses that slice of the recovery. In a threshold state, a defendant at 49% pays only their share while a defendant at 51% can owe everything. Identifying which system governs your case is the single most consequential question in any multi-defendant matter.
How Fault Percentages Get Assigned
Most states use comparative negligence to give each party, including the plaintiff, a percentage of responsibility. Your own share reduces what you can collect.
About a dozen states follow pure comparative negligence, letting a plaintiff recover something regardless of their fault share. A plaintiff 90% at fault still recovers 10%. Over 30 states use modified comparative negligence, which cuts off recovery entirely once the plaintiff’s fault reaches a threshold of either 50% or 51%. Under a 50% bar, a plaintiff exactly at 50% recovers nothing. Under a 51% bar, the same plaintiff still recovers but loses eligibility at 51%. A few states retain the old contributory negligence rule, which bars any recovery if the plaintiff was even 1% at fault.
Juries weigh each party’s conduct against the others. The Restatement (Third) of Torts points to the nature of each person’s conduct, the strength of the causal connection between the conduct and the harm, and the extent of the risk created by the behavior.1The American Law Institute. Restatement of the Law Third – Torts: Apportionment of Liability Witness testimony, expert analysis, accident reconstruction, and medical records feed that assessment. Reckless behavior that created a large risk almost always draws a higher percentage than minor or inadvertent conduct.
When the Injury Can’t Be Divided
Allocation is clean when each defendant’s contribution to the damage can be separated from the others. It breaks down when the harm is indivisible. Two factories polluting the same river, or two drivers whose combined negligence produces one catastrophic collision, illustrate the problem.
When an injury is truly indivisible, courts generally hold each defendant responsible for the entire harm and leave the financial split to contribution claims later. The burden falls on the defendants to prove the injury is actually divisible. If they can’t, each one is exposed to all of it.
Market Share Liability
A narrow branch of product liability law goes further. When a plaintiff knows the type of product that caused the harm but genuinely cannot identify which manufacturer produced the specific unit, some courts allocate damages by each manufacturer’s share of the relevant market. The California Supreme Court established this approach in Sindell v. Abbott Laboratories, where women harmed by the drug DES could not identify which company made the pills their mothers took decades earlier. Each manufacturer was held liable for the percentage of the judgment matching its share of DES sales, so long as the plaintiff had sued manufacturers representing a substantial share of the market.2Justia. Sindell v. Abbott Laboratories Most jurisdictions treat this as an exception limited to situations where identifying the specific manufacturer is genuinely impossible.
Getting Money Back From Co-Defendants
A defendant who pays more than their fair share can pursue the others. Two mechanisms do this work: contribution and indemnity.
Contribution
Contribution lets a defendant who has overpaid recover from co-defendants so each one bears an appropriate portion of the total. Many states adopted a version of the Uniform Contribution Among Tortfeasors Act to govern the process.3OpenCasebook. Uniform Contribution Among Tortfeasors Act (1955) Most states now allocate contribution based on each defendant’s comparative fault percentage rather than by equal pro rata shares.
A tortfeasor can only seek contribution after paying more than their share of the common liability. Timing is important. The statute of limitations for a contribution claim typically runs from the date of payment or the date a judgment becomes final, not from the date of the original injury. Windows of one to two years after payment or final judgment are common, but the exact deadline varies by jurisdiction.
Indemnity
Indemnity shifts the entire loss from one defendant to another rather than splitting it. It usually arises from a contract or from a situation where one party’s liability is purely derivative. A retailer held liable for selling a defective product may seek full indemnity from the manufacturer that created the defect. The retailer did nothing beyond stocking the product, so the manufacturer absorbs the loss.
What Happens When One Defendant Settles
A settlement by one defendant changes what the others owe, and courts use two main approaches to work out the credit.
Under a pro tanto (dollar-for-dollar) reduction, the remaining defendants get credit for the exact amount the settling defendant paid. A $100,000 settlement on a $500,000 claim leaves $400,000 of exposure. The risk is that a plaintiff accepts a low settlement from one defendant to keep a larger claim alive against the others.
Under a proportionate share reduction, the remaining defendants get credit for the settling defendant’s percentage of fault instead of the dollar amount. If the settling defendant was 40% at fault, the others owe 60% of the total damages regardless of whether the settlement was generous or cheap. This method is more common in comparative fault states because it fits the fault-based philosophy of the rest of the system.
The release document itself matters. A well-drafted release typically cuts off any contribution rights that non-settling defendants might otherwise assert against the one who paid.
Blaming an Absent Party
Defendants sometimes point at someone who is not in the lawsuit, whether the plaintiff chose not to sue them or they are immune from suit, and argue the absent party was the real cause. If the jury assigns fault to that “empty chair,” the named defendants’ combined share drops.
Whether this works depends on the jurisdiction. Many states allow fault to be apportioned to non-parties if the defendant offers enough evidence that a reasonable juror could find the non-party negligent. The plaintiff has every reason to keep the absent party off the verdict form, because in a several-liability state any fault assigned to an empty chair comes out of the plaintiff’s recovery. Nobody pays the empty chair’s share.
The tactic is most powerful in pure several liability states. In joint and several jurisdictions, allocating fault to a non-party matters less because the remaining defendants can still be tapped for the full judgment.
Not the Same as Vicarious, Strict, or Several Liability
The concurrent tortfeasor label describes the relationship between parties, not the underlying legal theory, and it is easy to confuse with related doctrines.
Several liability describes a payment rule: each defendant pays only their own share. Concurrent liability describes a factual situation and often triggers joint and several liability, so any one defendant can be reached for the whole judgment depending on the state’s rules.
Vicarious liability holds one party responsible for someone else’s conduct because of their relationship, such as an employer for an employee’s on-the-job negligence. Concurrent tortfeasors each must have engaged in their own wrongful conduct that contributed to the harm.
Strict liability removes the fault inquiry entirely. A manufacturer of a defective product is liable regardless of how careful the process was. Two manufacturers whose defective products combine to cause one injury can still be concurrent tortfeasors, because “concurrent” describes how their conduct converged, not the theory that makes each of them responsible.