Where more than one party causes a single indivisible harm, allocation rules determine each one’s exposure.

Traditional joint and several liability allows the claimant to recover the whole from any liable party, leaving that party to seek contribution. It places the risk of an insolvent defendant on the other defendants rather than on the claimant.

Several liability limits each defendant to its allocated share, placing the insolvency risk on the claimant. Many states have moved in this direction by statute.

Hybrid systems are common: joint and several liability above a fault threshold, or for economic damages only, or for particular claim types.

Comparative fault reduces the claimant’s recovery by its own share. Pure comparative systems allow recovery however great the claimant’s fault; modified systems bar recovery at fifty or fifty-one percent.

Non-party fault. Many statutes require the factfinder to allocate fault to settled and immune parties, which reduces the remaining defendants’ shares. The procedural requirements for putting a non-party on the verdict form — notice within a period, with specificity — are strictly applied.

Settlement credits. Pro tanto reduction by the amount paid, or pro rata reduction by the settling party’s share, with the choice materially affecting settlement strategy for every remaining defendant.