In Lugo Sanchez v. Puerto Rico Water Resources Authority, 105 D.P.R. 861 (1977), it held that an employer designated the "statutory employer", who, but for the fact that his subcontractor has provided the insurance, would be responsible under 11 L.P.R.A. section 20 for insuring certain employees, is, like the subcontractor, immune from suit, as provided by section 21. The court distinguished the "statutory employer" provided for under section 20 from a third party who can be sued: "For the purposes of art. 31 11 L.P.R.A. Sec. 32 of the Act, a third party liable for damages is a person unconnected with, alien, and separated from the juridical interaction that relates the statutory employer ... and the contractor ... with the State Insurance Fund in the mutual legal obligation of insuring their workmen and employees, pursuant to the provisions of the Workmen's Accident Compensation Act."