Alternative and market share liability are both theories of liability that a plaintiff might invoke when multiple defendants could have caused their injury and the plaintiff cannot prove which one caused the harm. In these cases, the court will apportion liability among the defendants who cannot prove that they did not cause or contribute to the plaintiff’s injury.
Alternative Liability
Alternative liability shifts the burden of proving causation from the plaintiff to the defendants. Each defendant must prove that they did not cause the plaintiff’s injury. Defendants who cannot make such a showing are held jointly and severally liable to the plaintiff. Joint and severally liability mean that each defendant is independently liable for the full extent of the plaintiff’s injuries. If the plaintiff is awarded a monetary judgment against all of the parties collectively, the plaintiff may collect the full amount of that judgment from any one of them.
Alternative liability might be used in cases where multiple medical teams treated a plaintiff, but the plaintiff cannot prove which defendant caused his injury. A court is likely to hold all defendants who cannot prove that they were not the source of the injury jointly and severally, liable.
Market Share Liability
Market share liability is a theory used in product liability cases when the plaintiff cannot prove which defendants produced the product that caused their injury. Under a market share liability theory, the court divides damages among the defendants who cannot prove that their product did not cause the plaintiff’s injury in proportion to each defendant’s relative market share of the product.
A lawyer will share that, for example, if ten different companies manufactured a drug that injured the plaintiff, but the plaintiff does not know which of the ten companies produced the specific drug they ingested, the plaintiff may sue all ten companies under a market share liability theory. The court will then apportion liability among any defendants that cannot prove that they did not produce the drug the plaintiff ingested based on their shares of the market of that drug.
For market share liability to apply, all defendants must have produced an identical product version. The plaintiff’s inability to identify the product manufacturer that injured them must be through no fault of their own. The plaintiff does not have to join all product manufacturers in the suit, but in most states, they must join enough to constitute a “substantial share” of the market. Other states do not require that the plaintiff enter any specific number of defendants, but the plaintiff’s total recovery will depend on how many defendants they join.
Whether the defendants are jointly and severally liable or severally liable only varies from state to state. Several liability means that each defendant is only liable for the damages they are responsible for. Therefore, the plaintiff cannot recover the entire amount of the judgment from any single defendant but must collect individual shares of their damages from each defendant.
Thanks to Eglet Adams for their insight on alternative and market share liability.