He was the editor of Revista Jurídica (Law Review) during the academic year 1940-1941 and in his last year at the Faculty of Law 1941-1942 he held the chair of Chancellor of the Alpha Chapter of the Phi Eta Mu Fraternity. After obtaining his law degree, Lugo was a legal official for Chief Justice of the Puerto Rico Supreme Court Emilio del Toro Cuebas and Associate Justice A. Cecil Snyder.
In 1961 he was appointed Associate Justice of the Supreme Court of Puerto Rico by Governor Luis Muñoz Marín.