The concept of joint and several liability is key to the tort system. It arises in many injury cases. For instance, you run a red light and strike another car. The car you are driving belongs to your employer. You may be liable for that act of negligence. Also your employer may be liable. The liability of the employer is known as vicarious. In other words the employer is only liable because you are her employee.
Joint And Several Liability Is A Powerful Tool
The liability that is imposed there is known as joint and several. As a result the plaintiff could sue the employee alone or could sue the employer alone. Or could sue both. Whatever judgment the plaintiff gets could then be collected against the employee solely. Or against the employer solely. Or against both. The plaintiff can only have one full recovery. Under this principle each defendant is 100% liable for the judgment. That is a principle that has been under attack lately. It can create circumstances wherein a defendant pays more than his fair share of any judgment. This is so if the other defendant cannot afford to pay.
Joint And Several Liability Shifts the Burden
The reason behind it is to make sure that the Plaintiff can obtain at least one full recovery. It then becomes the burden of those defendants against whom the judgment has been entered to fight among themselves as to sharing of that liability.
As to this personal injury concept and others see the pages on this site for a detailed explanation of tort principles. Also for more info about joint and several liability see the pages on Wikipedia.