Warren A. Koshofer

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Warren A. Koshofer

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Commercial Business Litigation

New York

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

Industry Association

  • The Risk Management Society (RIMS)

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.

Warren Koshofer is a partner in M&R’s New York office, where he handles commercial and business litigation matters involving, among other things, contract matters, intra-company disputes, insurance coverage and defense, environmental law, toxic tort defense, real estate disputes and transactions, due diligence and indemnification relating to company mergers and acquisitions, and construction related matters.

Warren represents clients—including Fortune 100 companies, partnerships, and high- profile individuals—at 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, manufacturing, financial and hospitality industries, he has also had several landmark victories in the chemical, energy, oil and gas sectors in litigation alleging, among other things, toxic exposures, product defects and Proposition 65 violations. Indeed, Warren regularly handles disputes that are at the intersection of law and science.

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.
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 hotel and gaming corporation in connection with environmental, risk management, and energy-related services agreement pertaining to an $8B 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 CERCLA Superfund site. The negotiations between and among the USEPA, 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 USEPA-driven Superfund settlements.
Environmental Defense: Successfully defended a client against the USEPA, which filed a complaint seeking penalties in excess of $1M for alleged regulatory violations. The USEPA alleged that the client operated a plant that leaked a hazardous substance into the air before being shut down by USEPA. 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 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 causing cancer in current and former students, teachers and area residents. On the strength of the legislative investigation showings, the toxic tort claims against the municipal client were dismissed on motion.
Proposition 65 Cases: Represented product manufacturers in California Proposition 65 cases relating to various products, including a bicycle manufacturer defending claims that the cables on its bicycles were subject to Prop 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 very 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.
Media Mentions
April 01, 2022

Law Firms’ Evolving Take on Sustainability

  • AV (Preeminent) peer-rated attorney, Martindale-Hubbell
  • Super Lawyers and in the Marquis' "Who’s Who in Law"