In a legal case, when more than one party, either working in concert or consecutively, engage in behavior that causes damage to a plaintiff, the court may permit the victim to sue each liable party for the entire amount of the damage, called either solidary liability or liability in solidum. In solidum is a Latin phrase that means in total or on the whole. In both solidary liability and liability in solidum, the plaintiff may choose to sue one party for the entire damage, sue more than one person jointly, or sue the parties consecutively if the full amount of the damage is not fully paid by the first defendant. Any payment made by one defendant toward the damage award owed to the plaintiff satisfies the obligation of the others toward the plaintiff. Liability in solidum cases arose during the late 1800s in order to spare the courts the difficult assignment of liability to each defendant and facilitate collection of damages for the plaintiff.
Although solidary liability and liability in solidum share the main consequence of the victim being able to seek relief from just one party, they are different in that solidary liability applies to defendants who have a contractual arrangement or work together in full knowledge and agreement. On the other hand, in solidum parties may have engaged in independent, concurrent acts, each of which contributed to a common damage. The opposite of in solidum liability is proportionate or pro rata liability, in which each defendant is liable only for his own share of the award. For example, a syndicate of banks agrees to advance a loan to a borrower, but the contract for the loan states that each bank is severally liable for its own contribution to the loan. If one bank fails to follow through on its portion of a loan, the borrower may only apply for relief against that one bank, not the other banks in the syndicate.
In the United States, courts use the term, joint and several liability, instead of liability in solidum. The basis for joint and several liability is the idea that the defendants bear the responsibility for dividing the liability, sparing the plaintiffs the costs of ongoing litigation and exposure to undercompensation if one of the defendants cannot pay his portion. Detractors of the principle complain about the injustice of a system that forces a minimally liable, "deep pocket" defendant, who may only distantly be involved in an occurrence, to pay the entire award in a lawsuit because the real culprit is insolvent. For example, imagine a case in which a drunk driver plows into a storefront, killing a patron. The shopper's family cannot collect anything from the bankrupt, unemployed driver, but their attorney also sues the store, hoping to cash in on a big settlement with the large chain.