Lillian Mateo-Santos obtained her Bachelor’s Degree in Business Administration from the University of Puerto Rico, Río Piedras Campus, in 1993 and a Juris Doctor degree from the University of Puerto Rico School of Law in 1996. In 1999, she obtained a degree of Masters of Laws (LLM) in Environmental and Energy of the Tulane University Law School. Before joining the Puerto Rico Energy Bureau, Ms. Mateo-Santos was a member of various law firms. Her private practice was focused on energy, environmental, land use and permitting matters, including administrative law litigation. On June 5, 2019, Ms. Mateo-Santos was elected 2nd Vice President of the Southeastern Association of Regulatory Utility Commissioners (SEARUC). She is a member of the American Bar Association and is admitted to practice law and notary law in Puerto Rico, and the United States Court of Appeals for the First Circuit.