6. Subject to the conditions of his contract and up to the amount stipulated, an insurer is directly responsible towards third parties for any damage covered by liability insurance.
Furthermore, up to the amount, for each automobile, prescribed in section 14, he cannot set up against them the causes of nullity or of lapse that might be set up against the insured.
He cannot be sued by the third parties before final judgment executory against the insured.
He may if necessary intervene in the action taken against the insured.
R. S. 1964, c. 232, s. 6.