What happens when more than one person is responsible for the same injury - the traditional rule that each is liable for the whole judgment, the modern rules in most states that limit it by share of fault or by type of damages, contribution between defendants, the effect of settling with one of them, and why the rule decides who actually pays when one defendant is uninsured or bankrupt.
Injuries are often caused by more than one person: two drivers, a manufacturer and a retailer, a property owner and a contractor, a hospital and a physician. Joint and several liability is the rule that governs how a judgment against several responsible defendants is collected. Under the traditional rule each defendant found liable for an indivisible injury is liable for the entire judgment, and the plaintiff may collect all of it from any one of them, leaving that defendant to seek contribution from the others. The rule exists to put the risk of an insolvent or absent wrongdoer on the wrongdoers who remain rather than on the injured person; its cost is that a defendant found only slightly at fault can end up paying for everyone.
Most states have modified the rule, and the modifications are what a plaintiff and a defendant now have to know. Some have abolished joint liability entirely, so that each defendant pays only its own percentage of fault as found by the jury (several liability). Many have adopted hybrids: joint liability only for a defendant whose fault exceeds a threshold percentage; joint liability for economic damages (medical bills, lost income) but several liability for non-economic damages (pain and suffering); joint liability where the defendants acted in concert or where the plaintiff was free of fault; or a reallocation rule under which an uncollectable defendant's share is spread among the others in proportion to fault. Several states also let a jury assign fault to a non-party - a settling defendant, an immune employer, an unknown person - which reduces what the defendants at trial must pay. Because the rules differ so much, the same accident produces different recoveries in different states.
A defendant who pays more than its share may seek contribution from the other liable parties, under a statute in most states, and indemnity where the law or a contract shifts the whole loss to another (a retailer sued for a manufacturing defect, an employer for an employee's act). Settlement with one defendant is governed by statute: in most states a good-faith settlement releases the settling defendant from contribution claims and reduces the plaintiff's judgment against the rest either by the settlement amount or by the settling defendant's share of fault, depending on the state. Where the rule of several liability applies, the plaintiff bears the risk of an under-insured defendant, which makes the identification of every responsible party and its insurance a central task before suit. Vicarious liability is different: an employer answerable for an employee's negligence is liable for the employee's full share, not a separate percentage.
The rule matters most at two moments: when deciding whom to sue, because in a several-liability state a defendant left out is a share of the loss left unrecovered, and when deciding whether to settle with one defendant, because the settlement credit rule determines what the remaining defendants will owe. A defendant with a small share of fault and deep insurance in a joint-liability state faces exposure well beyond its fault and should evaluate contribution and indemnity claims early. These are strategic questions decided by state statute, and a lawyer should be able to explain the local rule at the first meeting.
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