In civil law, plaintiffs have time limits in which to file a civil claim, collectively called "statutes of limitations." These laws are in place to ensure that claims are made while evidence is still fresh. They also help prevent the constant "threat" of a lawsuit hanging on indefinitely. Illinois civil statute of limitations laws impose a two-year time limit for personal injuries and a five-year statute of limitations for injury to personal property.
The clock typically starts running at the time an injury is suffered. But that's not always the case. It technically doesn't start until the "accrual of claims," which could be the point at which the injury (or its cause) is discovered. The so-called "discovery rule" allows a suit to be filed within a certain time after the injury is discovered or reasonably should have been discovered.
Additionally, the statute of limitation may be "tolled" -- or paused -- for a period of time. This may happen if the plaintiff was a minor (under 18) or mentally incompetent at the time the injury occurred. Also, statutes of limitation may be shortened through contract.