There are generally two types of "wrongful dismissal".
The first type involves cases where an employer, believing it has
cause for termination without notice, dismisses an employee for
cause only to have a court subsequently decide that there were
insufficient grounds to establish just cause for termination. In
that sense, the dismissal was "wrongful" because notice
of termination without cause should have been given.
The second type of wrongful dismissal involves cases where an
employer fails to give sufficient notice, or pay in lieu of notice,
for a termination of employment without cause. The
"wrongful" act is the employer's failure to give
proper notice of termination, contrary to an express or an implied
term of the employment contract.