A convincing justification for vicarious liability has proved elusive.  Courts refer to a grab-bag of justifications that reflect different approaches to tort law theorising prominent at different points of time.  This paper explores a justification for vicarious liability first proposed by the author of the eponymous Salmond test.  Salmond suggested that the justification for vicarious liability could be found in the problems of proof that arise when courts try to distinguish the tortious conduct of an employee from that of an employer.  Those difficulties arise because an employer is vested with authority to direct the conduct of an employee for the employer’s own benefit.  An employee may unduly prioritise compliance with the directions of the employer rather than give due weight to alternate considerations that might lead an employee to conduct herself different in the circumstances.  It can therefore be difficult to ascertain whether the damage suffered by the claimant was caused by the tortious conduct of the employee, the employer or a combination of both.  After examining a range of tools the courts have developed to address fact-finding difficulties in the law of torts, it is suggested that vicarious liability performs a similar role. A convincing justification for vicarious liability can therefore be found in the specific fact-finding difficulties that arise within the context of an employment relationship.