Vicarious liability is a form of a strict, secondary liability that arises under the common law doctrine of agency, respondeat superior, the responsibility of the superior for the acts of their subordinate or, in a broader sense, the responsibility of any third party that had the "right, ability or duty to control" the activities of a violator. It can be distinguished from contributory liability, another form of secondary liability, which is rooted in the tort theory of enterprise liability because, unlike contributory infringement, knowledge is not an element of vicarious liability.[1] The law has developed the view that some relationships by their nature require the person who engages others to accept responsibility for the wrongdoing of those others. The most important such relationship for practical purposes is that of employer and employee.[2]