A person who knowingly participates in a fiduciary’s breach may be liable although they owed no duty themselves. This is how advisers, counterparties and lenders are drawn into governance disputes.

Elements. An underlying breach of fiduciary duty; knowledge of the breach by the defendant; substantial assistance or participation; and damages.

Knowledge must generally be actual, not constructive. Negligence is not enough, and courts have consistently rejected a should-have-known standard in most jurisdictions.

Substantial assistance requires more than ordinary commercial dealing. A buyer negotiating hard is not aiding and abetting; a buyer that helps the fiduciary conceal the conflict or structures the deal to defeat the company’s rights may be.

Who gets named. Acquirers in a contested sale, investment banks, accountants, counsel in some circumstances, and competitors who hire away a fiduciary and receive the fruits of the breach.

Damages are typically joint and several with the fiduciary, which is often the point — the aider is solvent and the fiduciary is not.

Defensive practice. A counterparty told that a fiduciary is acting without board authority, or that a conflict exists, should insist on documented authorization. Proceeding after notice is the fact pattern that produces liability.