findings of quasi-judicial agencies in fields where they are deemed and held to be experts due to their special technical knowledge and training. [ 1 3 ]   The CA likewise erred when it ruled that where the illness supervened during employment, the presumption is that such illness arose out of the employment. Before P.D. No. 626, as amended, the employee need not present any proof of causation. It was the employer who should prove that the illness or injury did not arise out of or in the course of employment. [ 1 4 ]  However, P.D. No. 626, as amended, changed the system of compensation. As discussed in Government Service Insurance System,  this Court explicitly held that the concept of presumption of compensability and aggravation has been discarded by the new system. The purpose of this innovation was to restore a sensible equilibrium between the employers obligation to pay workmens compensation and the employees right to receive reparation for work-connected death or disability. This principle has been affirmed in a line of cases. [ 1 5 ]   WHEREFORE, the petition is GRANTED.  The Decision and Resolution of the Court of Appeals are REVERSED and SET ASIDE. The Decision of the Employees Compensation Commission dated August 19, 1999 is AFFIRMED.   No pronouncement as to costs.   SO ORDERED.     MA. ALICIA AUSTRIA-MARTINEZ Associate Justice