Maceira Zayas represents private companies, public entities, developers, and regulated professionals before Puerto Rico and federal agencies across the full administrative lifecycle: pre-application strategy, licensing, compliance program development, agency investigations, enforcement defense, administrative hearings, and judicial review under Puerto Rico's Uniform Administrative Procedure Act (Act 38-2017, 3 L.P.R.A. § 9601 et seq.) and the federal Administrative Procedure Act (5 U.S.C. § 551 et seq.).

The firm appears regularly before the Puerto Rico Energy Bureau (PREB); the Negociado de Telecomunicaciones (NET) of the Public Service Regulatory Board; the Department of Consumer Affairs (DACO); the Puerto Rico Treasury Department (Hacienda); the Office of Permits Management (OGPe); the Department of Economic Development and Commerce (DDEC); the Department of Natural and Environmental Resources (DRNA); the Puerto Rico Aqueducts and Sewers Authority (PRASA); the Puerto Rico Ports Authority; and professional licensing boards across regulated industries. At the federal level, the firm handles matters before the U.S. Environmental Protection Agency (EPA), the Federal Energy Regulatory Commission (FERC), the Federal Aviation Administration (FAA), the Federal Emergency Management Agency (FEMA) under the Stafford Act (42 U.S.C. § 5121 et seq.), the U.S. Department of Housing and Urban Development (HUD) in connection with CDBG-DR programs, the U.S. Department of Energy (DOE), and the U.S. Army Corps of Engineers. Maceira Zayas (MZLS) represents clients before Commonwealth agencies and their federal counterparts, with offices in San Juan and Washington, D.C.

The team includes Hon. Edgardo Rivera García, who served as Associate Justice of the Supreme Court of Puerto Rico from 2010 to 2024, and Jorge Alexis Meléndez Rivera, an attorney and licensed professional engineer who directs the firm's environmental and construction law practice.