Mayer Brown secures landmark victory for TC Energy in Delaware Supreme Court

Mayer Brown achieved a significant appellate victory on behalf of TC Energy Corp. in the Delaware Supreme Court, which reversed a $199 million judgment previously entered against the company in connection with its $13 billion acquisition of Columbia Pipeline Group Inc.

Serving as lead counsel, Mayer Brown successfully argued that TC Energy’s negotiation tactics during the 2016 transaction did not constitute unlawful conduct. The Delaware Supreme Court unanimously held that, while TC Energy’s approach may have been aggressive, it did not rise to the level of aiding and abetting a breach of fiduciary duty under Delaware law. The Court clarified that liability cannot be imposed based on “constructive knowledge” and reaffirmed that corporate acquirers are entitled to pursue the best available terms unless they have actual knowledge of, and actively participate in, a counterparty’s breach of duty.

“We are proud to have represented TC Energy in this important case, which reinforces the legal standards governing M&A negotiations and provides clarity for future transactions,” said Mayer Brown partner Brian Massengill. “The Court’s decision affirms that hard bargaining, without collusion or encouragement of fiduciary breaches, is not only permissible but expected in sophisticated dealmaking.”

The Mayer Brown team included partners Brian Massengill, Mike Olsen, and Linda Shi, and counsel Matt Sostrin in the firm’s Chicago office, and partners Nicole Saharsky and Minh Nguyen-Dang, and associate Carmen Longoria-Green in the firm’s Washington DC office. 

The case is In re Columbia Pipeline Grp. Inc. Merger Litig., Del., No. 281, 2024, 6/17/25.

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