The City of Montreal claimed taxes from Montreal Locomotive Works Ltd, which built a plant to manufacture tanks and gun carriages for the Minister of Munitions and Supply of Canada, "for and on behalf of the Government and as its agent".
If the company was occupying the premises where it built the plant merely as an agent, then it would not be liable for tax, but if it was carrying on business on its own behalf it could, under the British North America Act section 125.
In earlier cases a single test, such as the presence or absence of control, was often relied on to determine whether the case was one of master and servant, mostly in order to decide issues of tortious liability on the part of the master or superior.
It has been suggested that a fourfold test would in some cases be more appropriate, a complex involving (1) control; (2) ownership of the tools; (3) chance of profit; (4) risk of loss.
Again the law often limits the employer's right to interfere with the employee's conduct, as also do trade union regulations.