(a) In every action instituted by an employee claiming the benefits provided herein, the employer is bound to plead in his answer to the complaint the facts that led to the dismissal, and to prove that it was justified in order to be exempted from compliance with the provision of § 185a of this title. Likewise, in every suit instituted by an employee claiming the benefits provided herein, when the matter concerns an employee contracted for a certain term or for a certain project or job, the employer