Summary dismissal refers to when an employer fires a staff member instantly. The employee receives no notice nor pay in lieu of notice. This should only occur in response to gross misconduct, as when the employee behaves in this way, they have broken the trusted relationship between the employer and themselves.
Examples of gross misconduct which may justify summary dismissal include theft, discrimination, harassment, damage to company property, and fraud. When you are considering a summary dismissal for a staff member, remember that you must still follow due process. Otherwise, you may open yourself up to the risk of a wrongful termination suit.