Antonio joined the Firm in 1998, subsequently serving as one of the main advisors of the government entity in charge of the telecommunications privatization process. In addition to his involvement in the organization and sale of the national telecommunications entity, he was one of those responsible for drafting the legal instruments that currently regulate telecommunications in El Salvador. He was then appointed general director of Consumer Protection, for a period of two and a half years. In this position he gained first-hand experience with issues related to anti-competitive practices, regulation, and consumer protection practice.

In addition, he has worked as a professor of Economics, Constitutional Law and Philosophy of Law at the Dr. José Matías Delgado University since 2002. He is currently a professor of Constitutional Procedural Law.