Libby advises clients on federal air quality regulations, regulatory compliance, and litigation under the Clean Air Act (CAA). Before joining Beveridge & Diamond, she spent more than six years with the U.S. Environmental Protection Agency’s (EPA) Office of General Counsel, where she advised on federal air quality programs, developed federal regulations, and represented the agency in federal appellate litigation.

Most recently, Libby served as Assistant General Counsel for EPA's Air Toxics Practice Group, where she managed a team of ten attorneys responsible for rulemaking and litigation under CAA sections 112 and 129. She oversaw matters involving National Emission Standards for Hazardous Air Pollutants (NESHAPs), waste incineration rules, and other hazardous air pollutant requirements.

Previously, as an Attorney-Advisor in EPA's Air and Radiation Law Office, Libby advised on exceptional events, non-interference requirements for state implementation plans under Section 110(l), and startup, shutdown, and malfunction issues, including affirmative defense provisions. She also worked on NESHAP regulations affecting petroleum refineries, primary copper smelters, secondary lead smelters, and cyanide chemicals manufacturing facilities.

Libby has extensive federal appellate litigation experience, having served as EPA counsel in cases before the Third, Sixth, Ninth, Tenth, and D.C. Circuit Courts of Appeals. She coordinated with the U.S. Department of Justice (DOJ) on litigation challenging agency actions and participated in EPA's internal workgroup evaluating the impacts of the U.S. Supreme Court's decision in Loper Bright Enterprises v. Raimondo for agency decision-making.

Earlier in her federal government career, Libby worked in EPA's Office of Water, where she addressed water quality standards, rulemakings, and regional regulatory issues. She also held positions with the U.S. Department of Agriculture's Natural Resources Conservation Service and NASA through the Presidential Management Fellows Program.