Aaron P. Allan is the leader of Glaser Weil’s Environment and Energy practice. For more than two decades, he’s litigated cutting-edge and “bet the company” cases for a diverse range of business entities, including significant environmental and insurance coverage cases, toxic tort cases and real property litigation matters.

Aaron is sought after for his representation of publicly regulated water utilities in matters involving environmental and toxic tort claims brought under CERCLA and other environmental laws. He frequently handles complex insurance coverage issues on behalf of manufacturing companies, government entities, shopping centers, hoteliers, oil companies, solar energy companies, financial institutions, trustees and real estate developers, and has a track record of successfully helping clients obtain insurance coverage in a variety of contexts.

Aaron routinely assists clients with the following types of litigation and counseling matters:

  • Complex Environmental Litigation
    • Air Quality (Including Enforcement Defense and Permitting)
    • Asbestos/Mold/Lead Compliance, Litigation and Counseling
    • CERCLA/Superfund and Groundwater Cleanup Matters
    • Drinking Water Contamination Claims
    • Proposition 65 Defense and Counseling
    • Toxic Tort Defense
    • Solar Power Construction and Energy Credit Issues
  • Real Property Litigation
  • Business Litigation and Contractual Disputes
  • Insurance Coverage (Including Acquisition, Negotiation and Enforcement)

In addition to providing advice and counseling on environmental regulatory matters, such as air permitting, asbestos removal, drum recycling, Prop. 65 compliance and hazardous material management, Aaron helps clients manage environmental due diligence, environmental site remediation activities and liability risks associated with the sale, purchase or foreclosure of environmentally contaminated properties.

Aaron is also a musician and an avid mountain biker.


Aaron's notable experience includes his representation of: 

  • A client in managing a $7 million construction defect litigation in Boulder, Colorado, which successfully settled on the eve of trial.
  • A senior tech executive in a wrongful termination arbitration proceeding against a Nasdaq-listed technology company, which resulted in a successful eight-figure settlement achieved just prior to trial.
  • A major California real estate developer in a dispute with a major oil company over an oil field cleanup, which successfully settled after years of negotiation prior to filing any lawsuit.
  • A major California recycling company in managing environmental due diligence for the successful sale of the company.
  • A California real estate finance company in a bad-faith lawsuit and related jury trial against a well-known title insurance company.

Additional representative experience includes: 

Complex Environmental/Real Property Litigation
  • Defended an aluminum and titanium forging company against stormwater discharge allegations and Clean Water Act enforcement.
  • Represented drum recycling company accused of criminal conduct and resolved civil statutory penalties for violating stormwater discharge laws.
  • Prosecuted multiple cost recovery actions concerning environmentally contaminated properties in Central California on behalf of one of California’s largest-ever Chapter 11 bankruptcy estates.
  • Prosecuted claims based on construction disputes brought by owner of Southern California solar energy project against multiple parties.
  • Represented local government entity to resolve claims against adjoining landowner that involved more than 20 parties, including bankruptcy trustee and probate administrators.
  • Represented large, well-known oil companies to resolve the responsibility for cleanup of contaminated real property located in Central California.
  • Represented large well-known hotelier and successfully resolved flood damage claims based on historic California storm incidents, including 500-year storm.
  • Represented shopping center developer in claim against national chain based on failure to comply with contract requiring store opening.
  • Defended and successfully resolved indemnity claim based on alleged inadequate regulatory closure at former California aerospace facility.
  • Routinely advises companies with respect to acquisition of brownfield sites and due diligence issues arising in connection with real property acquisitions.
CERCLA/Superfund/Groundwater Cleanup
  • Prosecuted CERCLA and related common-law claims against major oil company involved in remediating open-pit mining operation at a federal Superfund site, including issues related to acid mine drainage, continuing tort theories, water rights and restoration damages.
  • Prosecuted claims in federal court against a municipality arising under CERCLA based on groundwater contamination caused by leaking sewer.
  • Defended CPUC-regulated water utility in proceedings brought to enforce environmental cleanup obligations relating to groundwater pumping and plume control.
  • Represented CPUC-regulated water utility in cost recovery negotiations for groundwater basin cleanup effort being managed by U.S. EPA.
  • Represented insurance company in subrogation action to successfully recover cleanup costs from the United States Department of Defense.
  • Represented CPUC-regulated water utility in appeal of order determining allocation of groundwater pumping rights among over 100 California entities.
  • Represented trust department of a large local bank to resolve environmental remediation issues for all properties being managed by the bank, including advice concerning potential lender liability protections under CERCLA and similar state laws.
Drinking Water Contamination Claims
  • Developed and successfully briefed to the California Supreme Court the immunity that the court afforded to CPUC-regulated water utilities in Hartwell v. Superior Court, 27 Cal.4th 256 (2002) based on the delivery of contaminated drinking water.
  • Defended regulated water utility against wrongful death claim based on alleged exposure to E. coli in connection with replacement of drinking water main.
  • Defended and resolved toxic tort claims against water utility based on allegations of contaminated drinking water.
  • Routinely counsels California water utilities on drinking water and groundwater issues.
Asbestos/Mold/Lead Matters 
  • Defended major machinery company against asbestos personal injury claim.
  • Provided insurance advice to CPUC-regulated water utility in connection with asbestos litigation.
  • Defended well-known hotelier against mold personal injury claim brought by tenant.
  • Counseled clients regarding lead paint exposure and removal issues.
  • Drafted protocols for handling lead and asbestos during construction, renovation and demolition activities.
Insurance Coverage
  • Represented insurance company in seeking contribution from other insurers in connection with food contamination claim.
  • Represented excess insurance carrier in prosecuting a bad-faith subrogation action brought against primary carrier resulting from a $24 million personal injury verdict.
  • Routinely provides advice, counseling and representation in negotiating and enforcing insurance coverage for environmental and real property claims.
  • Prosecuting coverage claim against title insurance company based on an alleged failure to pay out benefits after an unlawful subdivision.
Proposition 65 Defense and Counseling
  • Successfully defended and settled Prop. 65 enforcement claims.
  • Counseled clients regarding Prop. 65 compliance issues, including new regulations.
  • Evaluated client products and operations for Prop. 65 and other regulatory risks.
Air Quality Enforcement and Permitting
  • Represented major hotelier in resolving air permitting issues for one of the largest hotel developments in the world.
  • Successfully resolved regulatory enforcement claims brought by the California Air Resources Board based on alleged violation of consumer products emission standards.
  • Counseled clients and negotiated with state and local agencies regarding diesel truck and generator emission issues.


Awards and Recognition

Awards and Recognition

“500 Leading Litigators in America,” Lawdragon, 2022, 2024

"Litigation Star," Benchmark Litigation, 2020, 2022, 2023, 2024


Loyola Law School, J.D., Executive Editor of the Loyola International and Comparative Law Journal and member of the St. Thomas More Honor Society

University of California, Los Angeles, B.A., English Literature


  • California
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