Bank of Montreal v Stuart is a decision of the Judicial Committee of the Privy Council on appeal from the Supreme Court of Canada.

[4] John Stuart did not have much remaining assets himself, and his fellow shareholders were reluctant to invest any more money in the company.

John Stuart suggested to the bank that he obtain money and a guarantee from his wife, originally in the amount of $100,000.

The only lawyer involved in the transactions was Alexander Bruce, QC, who was simultaneously acting for the bank and for John Stuart.

"[8] Jane Stuart brought an action in the Ontario High Court of Justice to rescind the various mortgages and security interests which she had granted.

On 10 December 1907, the trial judge dismissed the action with costs, noting that "Mrs. Stuart is a lady of intelligence and refinement", who had been the sole executrix of her father's estate, totalling around $250,000.

He noted that John Stuart denied that he had exerted any undue influence over his wife, and also that she had received shares in the company from her husband and the other shareholders, worth about $23,500, in exchange for the guarantees.

The trial judge rejected the argument that a married women must always receive independent legal advice.

The other two judges, Moss CJO and Garrow JA, concluded that she was entitled to relief and would direct that the matter be remitted for trial.

Citing their own decision in Cox v Adams, they concluded that a married woman is always entitled to independent legal advice in transactions with her husband.

[12] At that time, the Judicial Committee of the Privy Council was the ultimate appellate body for the British Empire, including appeals from the Supreme Court of Canada.

[20] The case continues to be cited in Canadian legal sources and by the courts, as relevant to the issue of undue influence and relations between spouses.

Jane Stuart succeeded in establishing undue influence "even though her husband had put no pressure on her because none was needed, as 'she had no will of her own ... she was ready to sign and do anything he told her to do.

'"[26] The proposition of the case has modern value in business venture loans where final court of appeal decisions such as Royal Bank of Scotland plc v Etridge (No 2) are followed, which developed the proposition further, leading to the widespread independent provision of "Etridge advice" to a spouse or other joint owner not set to benefit from a transaction.