A statute of limitations is the time period (set by the laws in your state) in which you can file suit claiming compensations. The statute of limitations can differ from case to case depending upon the conditions, and can vary from as little as one year to as long as ten or more in civil suits.
Personal injury cases, which commonly are founded on negligence, have a tendency to have statutes of limitations in the area of two to three years, with special exemptions carved out for malpractice cases.
State regulation controls statutes of limitations, so if you are thinking of filing suit, be sure to check the statute of limitations in your state.