Larry has extensive experience negotiating federal and state environmental approvals, including Clean Water Act and Endangered Species Act permits for commercial, residential, public works and mining projects. He has also defended challenges to those permits ad approvals in Federal and state courts.

Larry handles matters regarding cleanup of the Chesapeake Bay including the impact of storm water on the Bay's water quality. He also sits on the Howard County Maryland Environmental Sustainability Board addressing water quality and climate issues.

He has authored multiple amicus briefs for major environmental cases beofre the United States Supreme Court. These included briefs for:

• SWANCC, Rapanos and Sackett, which involved the definition of Waters of the United States under the Clean Water Act;

• South Florida Water Management District v. Miccosukee Tribe, which centered on the Clean Water Act's definition of "discharge";

• Babbitt v. Sweet Home Chapter of Communities for A Great Oregon, which involved the Endangered Species Act's "take" definition;

• Bennett v. Spear covering the rights of property owners to sue under the Endangered Species Act (ESA); and

• S. Environmental Protection Agency v. Defenders of Wildlife dealing with the EPA's delegation of clean water permitting authority to states.

Larry has testified before Congress on proposed legislation to reform the ESA and is co-author of the Endangered Species Act Desk Book: A Guide to Endangered Species Law for the Environmental Law Institute (2nd Ed., 2010). He also authored The Water Supplies Guide To Wetlands Regulation and Management for the American Water Works Association (1996). While at Justice, he was lead counsel in NRDC v. EPA, which upheld major portions of the EPA's NPDES program and Bersani v. EPA, which upheld EPA's veto authority under Section 404(c) of the CWA. He also worked at EPA and spent a detail at the President's Council on Environmental Quality (CEQ) working on CEQ's NEPA regulations.

Larry was an adjunct professor at George Washington University and University of Baltimore Law Schools, where he taught courses on Endangered Species and Wetlands Law.