2 Answers

In employment law, constructive dismissal, also called constructive discharge, occurs when employees resign because their employer's behaviour has become so intolerable or heinous or made life so difficult that the employee has no choice but to resign. Since the resignation was not truly voluntary, it is in effect a termination. For example, when an employer makes life extremely difficult for an employee, to attempt to have the employee resign, rather than outright firing the employee, the employer is trying to effect a constructive discharge.
The exact legal consequences differ between different countries, but generally a constructive dismissal leads to the employee's obligations ending and the employee acquiring the right to make claims against the employer.
The employee may resign over a single serious incident or over a pattern of incidents. Generally, the employee must have resigned soon after the incident. http://en.wikipedia.org/wiki/Constructive_dismissal

Although not formally dismissed, the action of employer is tantamount to a dismissal. That is constructive dismissal.