What Are Alternative and Market Share Liability?

Personal Injury Lawyer

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 actually caused the harm. In these cases, the court will apportion liability among the defendants who are unable to 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 several liability means that each defendant is independently liable for the full extent of the plaintiff’s injuries, so that 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 is unable to 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 products liability cases when the plaintiff cannot prove which of several defendants produced the product that cause 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. 

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.

In order for market share liability to apply, all defendants must have produced an identical version of the product, and the plaintiff’s inability to identify the manufacturer of the product that injured them must be through no fault of their own. The plaintiff does not have to join all manufacturers of the product 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 join any specific number of defendants, but the plaintiff’s total recover will depend on how many defendants they join.

Thanks to the personal injury lawyer at Eglet Adams for their insight on breach of fiduciary duty.