Warren serves as a member on the firm's Environment and Natural Resources Group Steering Committee. His practice focuses on chemical regulation and biotechnology issues arising under the Toxic Substances Control Act (TSCA), the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the Food Quality Protection Act (FQPA), the Federal Food, Drugs and Cosmetics Act (FFDCA), the Emergency Planning and Community Right-to-Know Act (EPCRA), and related State and Federal laws. He assists large and small companies in the chemical and biotechnology fields obtain regulatory approvals for their products, and he helps clients address ongoing compliance and product stewardship issues. Warren's counseling in these areas typically involves issues such as: assisting manufacturers of chemical or biotechnology products understand their registration, premarket notification, testing and reporting obligations, and assisting manufacturers of crop protection products in protecting their data compensation rights. He also assists companies in their day-to-day compliance with pollution control obligations under the Clean Water Act, the Resource Conservation and Recovery Act (RCRA) and other statutes.

A substantial portion of Warren's practice is devoted to helping clients develop and implement corporate compliance programs, including environmental auditing programs and comprehensive environmental management systems. He also assists clients in identifying instances of potential non-compliance and defending against administrative investigations and enforcement actions. Warren has negotiated successful settlements in numerous enforcement cases, often involving complex supplemental enforcement projects (SEPs) and challenging economic benefit and BEN model issues.