Contact Info vCARD

T: +1 213.229.7567
F: +1 213.229.6567

Los Angeles Office
333 South Grand Avenue
Los Angeles, CA 90071-3197, USA


Patrick W. Dennis is a partner in the Los Angeles office of Gibson, Dunn & Crutcher LLP.  He is a member of the Environmental Litigation and Mass Tort Practice Group.  Mr. Dennis has extensive experience representing clients in general manufacturing, energy, banking, aerospace, real estate, construction, electronics, oil and gas, cement making, and lead recycling in a wide range of environmental matters.  He has substantial experience in the following areas:

Mr. Dennis is consistently named among the nation's leading environmental law attorneys.  In 2017, he was listed in Expert Guide's Energy and Environment Guide as a leading practitioner in the area of Environmental law.  Mr. Dennis was also recently published in Who's Who Legal's Enviornment 2017 Guide, which recognizes outstanding practitioners in various practice areas.  In 2012, 2013 and 2014 Best Lawyers named him Los Angeles Litigation – Environmental "Lawyer of the Year."  He was also selected by his peers for inclusion in The Best Lawyers in America© for the field of Environmental Law and Litigation-Environmental.  In 2017 Mr. Dennis was awarded the Legal 500 Hall of Fame for being a "leading lawyer" in Legal 500 for the past six consecutive years. In 2017, Mr. Dennis was nationally ranked as one of just ten "Leading Lawyers" in Environmental Litigation in The Legal 500 United States and in all prior years going back to 2009 he was ranked as one of just 10 or 11 such Leading Lawyers.  For 2010 through 2017, he is in the top tier, Band 1, ranking for California environmental law in Chambers USA: America's Leading Lawyers for Business. Mr. Dennis received the 2016 CLAY (California Lawyer Attorney of the Year) award in the Real Estate and Development category for his role in the redevelopment of the Hollywood Park racetrack into a world class football stadium to house the Los Angeles Rams for their return to Los Angeles.  In 2009, Mr. Dennis was elected to the prestigious American College of Environmental Lawyers by his peers.  He was the Chair and a founding member of the Los Angeles County Bar Association Environmental Law Section.  For 2013 -2017, Mr. Dennis is a Vice Chair of the Board of Trustees for the California Science Center Foundation.

Among other successful appellate arguments,  Mr. Dennis represented (1) the Atlantic Richfield Company in the successful Ninth Circuit Court of Appeal decision reported at Wilshire Westwood Associates v. Atlantic Richfield Corporation, 881 F.2d 801 (1988) (excluding refined petroleum products from CERCLA coverage under the so-called "petroleum exclusion"); and (2) the Climate Action Reserve in the successful California Second Appellate District decision reported at Our Children's Earth Foundation v. California Air Resources Board, 234 Cal. App. 4th 870 (2015) (upholding the validity of the offset protocols for voluntary carbon emission reductions as part of California's landmark Greenhouse Gas cap and trade regulations). 

He received a B.S. (Civil Engineering – 1976); M.S. (Mechanical Engineering – 1978); and a J.D./MBA (1982), all from the University of California, Los Angeles.  Mr. Dennis has practiced exclusively in the environmental law area since graduating from law school.


  • University of California - Los Angeles - 1982 - Juris Doctor
  • University of California - Los Angeles - 1982 - MBA
  • University of California - Los Angeles - 1978 - Master of Science
  • University of California - Los Angeles - 1976 - Bachelor of Science


  • California Bar