Tort law: Liability and remedies - Joint and several liability + Comparative responsibility + Market share liability

Where two or more persons are liable in respect of the same liability, in most common law legal systems they may either be:

jointly liable, or

severally liable, or

jointly and severally liable.

Joint liability.

If parties have joint liability, then they are each liable up to the full amount of the relevant obligation. So if a married couple takes a loan from a bank, the loan agreement will normally provide that they are to be "jointly liable" for the full amount. If one party dies, disappears, or is declared bankrupt, the other remains fully liable. Accordingly, the bank may sue all living co-promisors for the full amount.

However, in suing, the creditor has only one cause of action; for example, the creditor can sue for each debt only once. If, for example, there are three partners, and the creditor sues all of them for the outstanding loan amount and one of them pays the liability, the creditor cannot recover further amounts from the partners who did not contribute to the liability.

Comparative responsibility (known as comparative fault in some jurisdictions) is a doctrine of tort law that compares the fault of each party in a lawsuit for a single injury. Comparative responsibility may apply to intentional torts as well as negligence and encompasses the doctrine of comparative negligence.

Comparative responsibility divides the fault among parties by percentages, and then accordingly divides the money awarded to the plaintiff. The plaintiff may only recover the percentage of the damages he is not at fault for. If a plaintiff is found to be 25% at fault, he can recover only 75% of his damages.

There are several circumstances that make comparative responsibility intricate: when the plaintiff shares in fault for the damages, when a defendant who has a share of the fault cannot be included in the suit, when one of the defendants cannot pay, and when there are charges of both negligence and intentional torts in the same action.

Market share liability is a legal doctrine that allows a plaintiff to establish a prima facie case against a group of product manufacturers for an injury caused by a product, even when the plaintiff does not know from which defendant the product originated. The doctrine is unique to the law of the United States and apportions liability among the manufacturers according to their share of the market for the product giving rise to the plaintiff's injury.