A variation of contract can be either agreed or unilateral. An agreed variation is usually not controversial, for example an increase in pay.
An imposed variation can amount to a dismissal if either the employer resigns and claims constructive dismissal or the imposed contract amounts to a different contract.
Legal principle whereby an employer can be held liable for wrongful acts by his employees that have been committed in the course of their employment. Examples may include, negligent driving which causes injury, injuries caused by one employee to another, and theft by an employee from a client.
This principle does not usually apply to contractors as long as the employer has chosen the contractor carefully. However, there are some exceptions to this rule.