Tanya C. O'Neill



Tanya C. O’Neill is a partner and environmental business lawyer in the Environmental Regulation and Insurance & Reinsurance Litigation Practices with Foley & Lardner LLP. Having focused exclusively on environmental law for more than 15 years, Ms. O’Neill focuses her practice on the representation of bankruptcy trustees with regard to environmental trusts, both pre-effective date negotiations and due diligence and post confirmation management and remediation and conflict resolution; environmental due diligence related to mergers, acquisitions and multi-state transactions; and obtaining and negotiating insurance coverage for environmental contamination and insurance recovery; and environmental permitting, compliance and remediation. Ms. O’Neill regularly counsels sellers, buyers and related corporate counsel throughout the country regarding all aspects of environmental due diligence and related purchase and sale agreement negotiations, and liability allocation. Ms. O’Neill has been involved in the remediation of sites in more than 25 states, ranging from dry cleaners to mining operations, chemical and pesticide manufacturers to smelters and hazardous and radioactive waste disposal sites.

Presentations and Publications

Ms. O’Neill is a regular speaker on various environmental topics and a frequent speaker on environmental insurance coverage considerations and due diligence.

  • Speaker, “Environmental Issues in the Bankruptcy Process” (November 2016)
  • Speaker, "Basic Principles of Environmental Insurance," Lorman (October 2016)
  • Speaker, "Annual Environmental Law Update - Environmental Insurance Coverage" (September 2015)
  • Speaker, "Environmental Liabilities in Real Estate Transactions" (December 2014)
  • Speaker, "2013 Environmental Legal Developments and Implications for Wisconsin Businesses" (December 2013)
  • Speaker, "Siting Issues for Renewable Energy Projects," Foley & Lardner LLP (March 2013)
  • Speaker, "Basic Principles of Environmental Insurance," Lorman (August 2012)

She has authored and co-authored multiple articles. Some of her relevant publications include:

  • Contributor, "Environmental Insurance," ABA SEER Environmental Transactions and Brownfields Committee Year in Review, (February 2008, 2010, and 2011)
  • "Environmental Insurance for Risk Management in Real Estate Transactions," Bloomberg Corporate Law Journal, Volume 3, Issue 3, (Summer 2008)
  • "New ASTM Standard for Assessment of Vapor Intrusion," Foley & Lardner’s Legal News (March 2008)
  • "Environmental Insurance: Insurance as a Means of Transferring Risks in Environmental Liability Transfers," Environmental Transactions and Brownfields Committee Newsletter, Volume 10, No. 1 (February 2008)


Ms. O’Neill is a 1998 graduate of Drake University Law School (J.D. with high honors), where she was a member of the Drake Law Review and elected to the Order of the Coif. She has a bachelor’s degree in political science from the University of Wisconsin-Green Bay.

Admissions and Professional Memberships

Ms. O’Neill is admitted to practice in Wisconsin and before the Western and Eastern Districts of Wisconsin. She is a member of the Environmental Law Section of the Wisconsin Bar and the Milwaukee Bar Association, the Federation of Environmental Technologists, as well as the Natural Resources and Insurance Coverage Sections of the American Bar Association.