Vicarious liability is a form of 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.

Employers' liability

Employers are vicariously liable, under the respondeat superior doctrine, for negligent acts or omissions by their employees in the course of employment. For an act to be considered within the course of employment it must either be authorised or be so connected with an authorised act that it can be considered a mode, though an improper mode, of performing it. Courts sometime distinguish between an employee's "detour" or "frolic". For instance, an employer will be held liable if it is shown that the employee had gone on a mere detour in carrying out their duties, whereas an employee acting in his or her own right rather than on the employer's business is undertaking a "frolic" and will not subject the employer to liability. Neither, generally, will an employer be held liable for assault or battery committed by employees, unless the use of force was part of their employment (e.g. police officers, nightclub bouncers), or they were in a field likely to create friction with persons they encountered (e.g. car re-possessors). However, the employer of an independent contractor is not held vicariously liable for the tortious acts of the contractor, except where the contractor injures someone to whom the employer owes a non-delegable duty of care, such as where the employer is a school authority and the injured party a pupil.

Employers are also liable under the common law principle represented in the Latin phrase, "qui facit per alium facit per se", i.e. the one who acts through another, acts in his or her own interests. This is a parallel concept to vicarious liability and strict liability in which one person is held liable in Criminal Law or Tort for the acts or omissions of another.

Principals' liability

The owner of an automobile can be held vicariously liable for negligence committed by a person to whom the car has been loaned, as if the owner was a principal and the driver his or her agent, if the driver is using the car primarily for the purpose of performing a task for the owner. Courts have been reluctant to extend this liability to the owners of other kinds of chattel. For example, the owner of a plane will not be vicariously liable for the actions of a pilot to whom he or she has lent it to perform the owner's purpose.