Who May Be Responsible Under Michigan Law
The answer depends on the theory that fits the facts, and the parties differ for each.
Under premises liability, the potential defendants are the people or businesses that owned or controlled the property: a trampoline park operator, a landlord of the building, or a homeowner. A negligence claim asks four things: whether the defendant owed the injured person a duty of care, whether it breached that duty, whether the breach caused the injury, and what damages resulted. Negligent supervision follows the same elements, focused on the person or business responsible for watching jumpers.
If the equipment failed, the companies that made or sold the trampoline or a component may be answerable under product liability. For the injured person, the question becomes whether the product was defective and whether that defect, rather than the fall alone, caused the injury. An accident alone does not show a defect, and the age of the product can matter; as noted above, Michigan treats proof differently for a product in use for 10 years or more.
When more than one person contributed, Michigan spreads the fault among all of them. Under section 600.6304 of the Michigan Compiled Laws, the jury, or the court without a jury, finds each plaintiff's total damages and a percentage of fault for every person who contributed to the injury, including nonparties and people released from liability, whether or not they were or could have been named. The trier of fact weighs both the nature of each person's conduct and how closely it caused the harm. For someone hurt at a park, that means the operator, a manufacturer and others can each carry a share, and the injured person's own share is counted too.
The practical questions to weigh are who owned or ran the place, who made or sold the equipment, and who was supervising. An attorney can help sort out which of those parties the facts actually reach.