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ProfessionalsWilliam J. O'Brien

William J. O'Brien

Tel: +1-212-373-3404
Fax: +1-212-492-0404

New York

1285 Avenue of the Americas
New York, NY 10019-6064
Fax: +1-212-492-0404

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Bar Admissions 

William J. O'Brien is counsel in the Environmental Law Group and a member of the firm’s Climate Change Working Group. Bill has advised various private investment funds on the environmental aspects of investments in private and public companies and the acquisition of portfolio companies, including conventional and alternative energy companies. He has also advised on numerous financings and securities offerings. He has written and lectured on various aspects of environmental law, including environmental disclosure requirements in securities offerings, parent corporation liability for environmental obligations and environmental law aspects of real property transfers.

Chambers USA recognizes Bill as a leading lawyer in transactional environmental law, with sources calling him “very business-focused and a great practitioner.” Bill has also been recognized by Super Lawyers and the International Who's Who of Business Lawyers for his work in environmental law.

Bill's recent representations include:

  • Elanco Animal Health Incorporated in its $7.6 billion acquisition of the animal health business of Bayer AG;
  • Salini Impregilo S.p.A. in the $555 million sale of the Plants & Paving division of its US subsidiary Lane Construction Inc. to Eurovia SAS, a company of the Vinci Group;
  • C&D Technologies, Inc., a portfolio company of KPS Capital Partners, LP, in its acquisition of Trojan Battery Company, LLC from Charlesbank Capital Partners, LLC and other shareholders;
  • Honeywell, a Fortune 100 software-industrial company, in its spin-off of Garrett Motion Inc., Honeywell's former Transportation Systems business;
  • Ingersoll-Rand plc in the merger of its Industrial business with Gardner Denver Holdings, Inc, a provider of industrial equipment and technologies, creating a $15 billion global leader in mission-critical flow and industrial technologies;
  • KPS Capital Partners, LP in several matters, including:
    • in connection with its $1.8 billion acquisition of Howden; and
    • along with International Equipment Solutions, LLC, a portfolio company of KPS, in the $690 million sale of the attachments division of International Equipment Solutions to Stanley Black & Decker, Inc.
  • Bicent Power Company LLC, an affiliate of Beowulf Energy and Natural Gas Partners, in connection with an agreement to acquire Northwestern Corp.’s 30 percent interest in Colstrip Unit 4, a 740 MW coal-fired facility, for $404 million in cash;
  • Cenovus Energy Inc., a wholly-owned subsidiary of EnCana Corporation, in connection with Rule 144A/Regulation S offering of $3.5 billion of senior notes; and
  • Husky Energy Inc. in connection with a public offering of $1.5 billion of debt securities.

In addition, Bill has an active pro bono practice. He recently advised Green Chimneys Children's Services on its merger with Clearpool, Inc. He has also advised on a number of transactions for the Trust for Public Land, a nonprofit, land conservation organization.

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