La. Code Civ. Proc. art. 2790

A. At a hearing to enforce a confirmed registered support order, the obligor may present only matters that would be available to him as defenses in an action to enforce the support order in the rendering court. If he shows to the court that an appeal from the order is pending or will be taken or that a stay of execution has been granted, the court shall stay enforcement of the order until the appeal has been concluded, the time for appeal has expired, or the stay order has been vacated, upon satisfactory proof that the obligor has furnished security for payment of the support ordered as required by the rendering court. If he shows to the court any ground upon which enforcement of the confirmed registered support order may be stayed, the court shall stay enforcement of the order for an appropriate period if the obligor furnishes the security for payment of the support ordered that is required by law.

B. Arrearages which accrue prior to registration of a support order shall not be modified unless there is a pending petition for modification at the time of registration of the support order. Any such modification shall be retroactive only to the date of filing of the petition for modification.