Industry Associations

  • The Risk Management Society (RIMS)

Bar & Court Admissions

  • State Bars of California, New York, New Jersey and Pennsylvania
  • U.S. Court of Appeals for the Ninth and Third Circuits
  • U.S. District Court for the Eastern, Central, Southern and Northern Districts of California
  • U.S. District Court for the Southern and Eastern Districts of New York and New Jersey

Professional Affiliations

American Bar Association

California State Bar Association

New Jersey State Bar Association

New York State Bar Association

Community Involvement

Agoura-Oak Park Youth Football

Agoura Pony Baseball 

Make a Wish Foundation

March of Dimes

United Way


Rutgers University School of Law, J.D.

Rutgers University, B.A. 

Photo of Warren A. Koshofer

Warren A. Koshofer

New York
T: 212.730.7700
F: 212.730.7725
Representative Matters
Full Bio

Warren Koshofer is a partner in M&R's New York office, where he handles commercial litigation matters involving mass and toxic torts, product manufacturing and liability, insurance, environmental law, real estate, and construction and contract disputes. Warren represents clients—including Fortune 100 companies, partnerships, and high-profile individualsat the state and federal trial and appellate court levels, as well as before administrative law courts, regulatory agencies, and in alternative dispute resolution forums across the country.

While Warren's cases primarily touch upon the insurance, environmental, and hospitality industries, he has also had several landmark victories in the manufacturing, chemical, and oil and gas sectors in litigation alleging product liability exposure. Likewise, Warren regularly handles disputes at the intersection of law and science.

Community Involvement

Warren has long been involved with various civic and community organizations, and has served as a board member for the United Way, the Make-a-Wish Foundation and the March of Dimes. He has also contributed to the youth of Southern California by serving on the boards of several different youth sports leagues.

Awards & Recognitions

Over the years, Warren has been recognized by Martindale-Hubbell as an AV (Preeminent) peer-rated attorney, the highest possible Martindale attorney rating for legal ability and professional ethics, and has been named to the list of Southern California Super Lawyers and in the Marquis’ “Who’s Who in Law.” 

Representative Matters

Acquisitions: Represented a prominent hotel and gaming corporation in the acquisition of competing corporations and hotel properties and the disposition of various hospitality and gaming related properties and businesses. The value of the acquisitions and dispositions exceeded $100M.

Aerospace Defense: Represented an aircraft component manufacturer in the defense of more than 60 lawsuits brought on behalf of passengers in a highly publicized air crash disaster case off the coast of Brazil.

CERCLA Defense: Represented a global insurance company in prosecuting a CERCLA contribution action against the United States Department of Defense pertaining to perchlorate contamination at a former ammunition manufacturing site. After aggressive litigation in federal court, the case settled in a favorable manner.

Due Diligence: Conducted due diligence on behalf of banks and other financial investors associated with contemplated new investments or loans, particularly with respect to environmental and litigation risks.

Environmental and Due Diligence: Represented a prominent hotel and gaming corporation in connection with the provisions of an environmental, risk management, and energy-related services agreement pertaining to an $8B mixed-use construction project in Las Vegas, Nevada.

Environmental Defense: Negotiated a first of its kind $400M joint water supply/contaminant cleanup project on behalf of a manufacturer alleged to have contributed to the contamination of a large Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Superfund site. The negotiations between and among the U.S. Environmental Protection Agency (U.S. EPA), U.S. Attorney General’s Office, several water supply companies, and numerous potentially responsible parties lasted for more than a year, with the resulting project serving as a model for future U.S. EPA-driven Superfund settlements.

Environmental Defense: Successfully defended a client against the Environmental Protection Agency (EPA), which filed a complaint seeking penalties in excess of $1M for violations of the Clean Air Act and the Emergency Planning and Community Right-to-Know Act. The EPA alleged that the client operated a plant that leaked a hazardous substance into the air before being shut down by EPA. Choosing to push back against the proposed penalties versus a merit-based challenge, the dispute was favorably resolved for $5,000.

Insurance Company Consumer Litigation: Represented a large international insurance company sued by a public company policyholder contending that an insurance product was illusory, illegal, and evidenced a pattern and practice justifying over $100M in damages. Devised a defense strategy that included filing suit against the policyholder for failing to pay certain policy premiums. Through litigation, secured a dismissal of the plaintiff's lawsuit and recovered approximately $5M on client's behalf.

Insurance Coverage/Bad Faith: Represented a prominent insurance company in the defense of an arbitration proceeding where the insured, under commercial general liability (CGL) insurance policies issued by the client, sought the return of several million dollars paid by the insured for, among other things, deductible obligations. After an aggressive defense, the case ultimately settled at mediation with the insured paying the insurer several million dollars, rather than the other way around.

Insurance Coverage: Represented product manufacturers in lawsuits with their liability insurers arising out of environmental and toxic tort claims. Overcame numerous challenges by the insurers, including claims that underlying layers of coverage were not exhausted and occurrences did not take place in particular policy years, to drive the insurers to the settlement table.

Insurance Defense: Represented a global insurance company in the defense and successful resolution of more than $100M in complex environmental claims. 

Municipality Toxic Tort/Legislative Investigation: Successfully launched a legislative investigation on behalf of a municipality client into the environmental conditions at a prominent high school, arising out of allegations that the operation of an oil well immediately adjacent to the high school was posing serious health risks to teachers, students and neighboring property owners. 

Proposition 65 Cases: Represented product manufacturers in California Proposition 65 cases relating to various products, including, for example, a bicycle manufacturer defending claims that the cables on its bicycles were subject to Proposition 65 disclosures.

Securities Fraud Defense: Represented an investment banking firm in defense of a securities fraud case alleging hundreds of millions of dollars of losses stemming from an alleged pump and dump stock scheme.

Toxic Tort Defense: Represented a chemical manufacturer in the defense of more than 80 separate toxic tort cases filed by teachers and students of an elementary school which neighbored a plating operation site where the client's chemicals were allegedly used. Led the defense to a favorable settlement on client's behalf.

Toxic Tort Defense: Represented a multinational corporation in the defense of a toxic tort case filed by more than 1,500 residents claiming injuries due to the ingestion of contaminated drinking water. Was a key member of the joint defense group, which after numerous appeals, including to the California Supreme Court, achieved a highly favorable settlement.