When can an employee say no to the boss or sue for wrongful dismissal?  This is an interesting question without a simple answer.  The answer depends on the particular circumstances of the direction given by the employer and supervisor.  

Employees must obey all lawful orders by their employers and supervisors, failing which they risk being dismissed for “just cause”.  On the other hand, employees need not follow unlawful orders, and if a dismissal occurs for refusal to do something that is found to be an unlawful order, the employee would be able to successfully sue for wrongful dismissal. If the employee was regularly required to carry out unlawful activities the employee could in some circumstances bring the employment to an end and sue for construcive dismissal, on the theory that the employer had in effect discharged the employee by requiring the employee to act unlawfully.

Martin Sheard was interviewed on this subject by the Vancouver Sun recently.  

Read the article When can a Worker say no to the Boss?