Robert Thornton specializes in advising state and regional infrastructure authorities on environmental issues regarding large infrastructure projects.  He has successfully defended more than $12 billion in regional infrastructure improvements against federal and state environmental challenges.

His work is well respected by his colleagues and clients who have ranked him among the nation's top environmental lawyers.



Los Angeles Light Rail Transit Project. Lead counsel in successful defense of $1.5 billion rail transit project in west Los Angeles in litigation through the California Supreme Court. Neighbors for Smart Rail v. Exposition Metro Line Construction Authority, 57 Cal. 4th 439 (2013).

Honolulu Rail Transit Project. Successful defense of 20 miles, $5 billion Rail Transit Project in NEPA, Section 4(f) and National Historic Preservation Act litigation. Honolulutraffic.com v. Federal Transit Administration, 742 F.3d 1222 (9th Cir. 2014).

Arizona Dep't of Transportation - South Mountain Freeway Project. Lead counsel to ADOT in successful defense of 20-mile South Mountain Freeway Project in Phoenix against NEPA, and Section 4(f) challenges. Protecting Arizona’s Resources & Children v. FHWA, U.S. Dist. Ariz Case Nos. CV-15-00893; 012121 (D. Ariz. Aug. 19, 2016, Granting ADOT’s Motion for Summary Judgment). The project is currently under construction, and on December 8, 2017, the Ninth Circuit Court of Appeals unanimously rejected two challenges to the 2016 decision, No.16-16586, No. 16-16605, --- Fed. Appx. ----, 2017 WL 6146939 (9th Cir. Dec. 8, 2017) (memorandum op’n).

Orange County Transportation Corridor Agencies. Devised and implemented a successful environmental compliance strategy to defend against twenty lawsuits challenging $3 billion in regional transportation improvements in Southern California. Laguna Greenbelt Inc. v. United States Department of Transportation, 42 F.3d 517 (9th Cir. 1994).

San Diego Expressway (SR 125). Successfully obtained state and federal environmental clearances and permits for development of a 10-mile toll highway in San Diego. Subsequently successfully defended against complex state and federal litigation brought by several environmental groups on CEQA, NEPA, ESA, and Clean Water Act. Center For Biological Diversity et al. v. Federal Highway Administration, 290 F.Supp.2d 1175 (S.D.Cal. 2003).

Pacific Lumber Company – Headwaters Forest Transaction. Served as special endangered species and real estate counsel to Pacific Lumber Company on its sale of the Headwaters Forest to the California and U.S. governments. Concurrently developed a 211,000-acre HCP - the largest private timber HCP to date and the first timber HCP to address endangered and threatened salmon.

Imperial Irrigation District Water Transfer Project. Served as environmental counsel for the IID/San Diego County Water Authority Water Conservation and Transfer Project. Work involved negotiating and obtaining federal and state environmental approvals for the nation's largest agriculture to urban water transfer project.

Central/Coastal Orange County Natural Community Conservation Plan/HCP. Represented the participating landowners in negotiations with the California Department of Fish and Game and the U.S. Fish and Wildlife Service concerning the development of the first Natural Community Conservation Plan approved in California. Efforts resulted in the establishment of a 38,000 acre habitat reserve, while allowing compatible development of public infrastructure and private projects over a large portion of Orange County.

Kern Water Bank Natural Community Conservation Plan/Habitat Conservation Plan. Counsel to public agency on NCCP and HCP regarding nation’s largest groundwater storage project. Successfully defended water bank project against CEQA and other environmental challenges.



Blog Posts

Speaking Engagements



Community & Professional

California Building Industry Association, Member

Orange County Building Industry Association, Member

Urban Land Institute, Member


Honors & Recognitions

Recognized as the "Lawyer of the Year" for Land Use and Zoning Law in Orange County by Best Lawyers in America©, 2022

Individual recognition for Environment in California by Chambers USA, 2013-2023

Included in The Best Lawyers in America© for Land Use and Zoning Law and Litigation - Environmental, 2021-2024

Included in The Best Lawyers in America© for Environmental Law, Land Use and Zoning Law, and Litigation - Environmental, 2003-2020

Listed, The Legal 500 United States, Industry Focus - Environment - Litigation, 2020, 2023

Ranked as one of the nation's top 10 environmental lawyers by United States Lawyer Rankings, 2006-2020

Selected to the Southern California Super Lawyers list, 2004-2020

Chosen as one of Law360's Environmental MVPs, 2016

Named to National Law Journal's list of "Top 50 Litigation Trailblazers & Pioneers," 2014

Named a Top Rated Lawyer in Land Use and Zoning by Martindale-Hubbell and American Lawyer Media, 2013

AV Preeminent® Peer Review Rated by Martindale-Hubbell



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