You must bring an action against every person who caused your injury. The negligence of two drivers, for example, may have produced a collision in which you were injured as you walked across a street. According to traditional legal principles, each driver could be held 100 percent liable to you. In a more recent legal trend, however, many jurisdictions have abolished such joint and several liability and each defendant, known legally as a joint tortfeasor, becomes responsible for only that proportion of the harm he or she caused. This is the rule of comparative negligence, which exists in most states, and is discussed more fully on page 525 and in chapter 11, "Automobiles."