7 March 2026

Understanding Undue Influence on a Will Upon Death

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Claims of undue influence over the deceased are frequently brought before the courts when an interested party wishes to contest a will.

In a recent decision, the Quebec Superior Court reiterates the criteria applicable to actions involving claims of undue influence over the deceased.

Undue Influence

Legal Basis of Undue Influence

Undue influence is the equivalent of deceit and fraud in civil matters, but applied to the specific case of a testator making a legacy that they would not have otherwise made had it not been for the undue influence of the persons being prosecuted.

Qualification of Undue Influence

In the decision Succession de Charette (2017 QCCS 1381), the Quebec Superior Court reiterates that it is not inherently unlawful for a person to curry favor with a testator. To be illegal and constitute undue influence, the defendants’ maneuvers must be fraudulent. For example, maneuvers that “are accompanied by artful practices, such as intercepting correspondence or preventing visits, or systematically disparaging close relatives” constitute undue influence:

[233] To vitiate a testator’s consent, the maneuvers must be fraudulent and must have been decisive in how the testator made their will. Furthermore, it is well established that it is not inherently unlawful for a person to curry favor with a testator. Professor Beaulne explains the concept of undue influence as follows:

690 – Undue Influence or Suggestion – Deceit is no longer included in the list of defects of consent. […] Nevertheless, it must be considered that a will can be annulled for deceit, i.e., when fraudulent maneuvers have occurred and these have genuinely provoked the testator’s decision. In gratuitous transfers, particularly in wills, the terms undue influence and suggestion, expressions borrowed from Old Law, are often used in this context.

691 – Necessity of Fraudulent Maneuvers – It is not inherently unlawful to curry favor with a testator. Thus, showing great zeal towards a sick person or multiplying expressions of affection towards them, when in fact one seeks to be appointed as a legatee, is not in itself a cause for nullity, nor is calling a notary and giving them instructions regarding the will to be prepared. As the Court of Appeal stated:

To establish undue influence, one must prove the existence of deceitful or fraudulent maneuvers. It is not enough to demonstrate that the person merely tried to curry favor with the testatrix, or in Ronald’s case, expressed his desire to become the owner of the residence where he lived with his mother.

692. However, acts of undue influence become fraudulent when they are accompanied by artful practices, such as intercepting correspondence or preventing visits, or systematically disparaging close relatives. This was reiterated by the Court of Appeal in the Gauthier case:

The defendants went beyond mere suggestions or advice to the testator. Their attitude exhibits a fraudulent character leading to the nullity of the will, as these defendants seized control of the testator’s will to suggest how to make their will […].

693. Furthermore, the fraudulent maneuvers must have been decisive in the consent. Therefore, a causal link must be established between the actions taken by the person accused of undue influence and the content of the will, as it is essential that these actions influenced the testator’s consent. It is always up to the person alleging undue influence to prove it, and mere suspicions are not enough to establish it: they “[…] must convince the Court that it was decisive on the wishes expressed in the contested will.” The evidence can be indirect, but it must be preponderant. […]

– Succession de Charette (2017 QCCS 1381)

Burden of Proof for Undue Influence

Since the deceased is obviously no longer present to give their version of events, proof of undue influence is generally made through presumptions of fact:

[234] Proof of undue influence is generally made using presumptions of fact which, as already mentioned, must be based on serious, precise, and concordant evidence, and there is no reversal of the burden of proof.

– Succession de Charette (2017 QCCS 1381)

However, the absence of direct evidence is a significant obstacle to establishing sufficient proof for a court to conclude undue influence over a deceased person. Moreover, the Quebec Court of Appeal specifies that actions for undue influence are often difficult to establish:

[95] There is no direct evidence here that the respondent or his sister diverted the testator’s will through fraud. It should be noted, however, that proof of undue influence is often difficult to establish. Of course, the presumed victim of the maneuver is no longer available to give their version of events. Secondly, as can be read in Fauteux v. Chartrain, “it is rare for the perpetrator of the maneuvers employed, who is to benefit from the gratuitous transfer, to act directly or openly; if cunning, they prefer to take oblique and concealed paths that will lead more surely and discreetly to their ends.” Furthermore, the law of gratuitous transfers is traditionally rather permissive regarding the persuasion, even persistent, that a person can exert on a donee or legatee, as long as it does not fall into fraud: French authors Terré, Lequette, and Gaudemet indeed write that the requirement of deceit in testamentary matters is not satisfied “when there has only been flattery of the disposer’s tastes or quirks, or manifestations of devotion – sincere or simulated – likely to arouse affection”

– Larocque v. Gagnon, 2016 QCCA 1237

In summary, it is important to emphasize that devotion, even simulated, intended to arouse the affection of the deceased, is not relevant in assessing the presence of undue influence. Therefore, demonstrating that a third party suddenly became devoted at the end of a deceased person’s life with the aim of obtaining a modification to their will will matter little. The burden of proof is, in fact, much greater and requires demonstrating that the defendants seized control of the testator’s will to suggest how to make their will.

Written by: Jasmyne Bouchard

Jasmyne Bouchard

Attorney

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