The usual types of mistakes break into two areas- that the will was not properly executed in accordance with established principles ,or the will itself does not make sense, is ambiguous, and needs to be constructed and interpreted.
Section 59 of WESA provides a new section allowing the court to rectify a will if the court determines that the will fails to carry out the will maker’s intentions because of:
1) an error arising from an accidental slip or omission;
2) a misunderstanding of the will maker’s instructions;
3) A failure to carry out the will maker’s instructions.
The court further allows for extrinsic evidence, that is evidence relating to the circumstances under which the will instructions were given and the will executed ,including evidence of the will maker’s intent, in order to prove the existence of the circumstance described in section 1 aforesaid .
For further reading on the construction or interpretation of wills, also see blogs on this site dated September 8,2011
June 1, 2012
April 20,2013 and
June 2, 2013.
The general guidelines of case law with respect to interpretation and construction of wills is as follows:
The goal in interpreting a will is to give effect to the testamentary intentions of the testatrix for the distribution of her estate: Rondel v. Robinson Estate, 2011 ONCA 493, 337 D.L.R. (4th) 193, at para. 23.
 The Ontario Superior Court of Justice in Re Kaptyn Estate, 2010 ONSC 4293, 102 O.R. (3d) 1, (“Kaptyn Estate”) helpfully summarized many of the principles relating to the interpretation and construction of wills:
a) The court will seek to determine the actual intention of the testator, as opposed to an objective intent presumed by law (para. 31).
b) Other cases interpreting words in other wills are of little assistance since the task is to interpret this testator’s subjective intentions (para. 32).
c) There is a distinction between interpretation and construction of a will. Interpretation seeks to determine the testator’s subjective intentions from the words used in light of the surrounding circumstances. Rules of construction are a default process turned to by the courts when the testator’s actual intentions cannot be ascertained (para 34).
d) The starting position of the court is the “armchair rule”, where the court puts itself in the place of the testator at the time when he made his will. This allows consideration of some extrinsic evidence of the surrounding circumstances known to the testator as might bear on his intentions (para. 35).
e) The authorities distinguish between admissible and inadmissible extrinsic evidence in interpreting a will (paras. 35-38):
i. “indirect extrinsic evidence” of the surrounding circumstances known to the testator at the time he made the will is generally admissible. This includes evidence of such things such as the testator’s occupation and property and financial situation; his relationships with family and friends; and natural objects of his grant;
ii. “direct extrinsic evidence” of the testator’s intentions is generally inadmissible. This is so as to preserve the will itself as the primary evidence, and to avoid the situation of an “oral will” displacing the written form. However, there is an exception where there is an “equivocation”, namely, where the will describes two or more persons or things equally well. In that situation, the law will allow evidence of the testator’s intention. Examples of inadmissible direct evidence are such things as notes or statements of the testator as to his intention, or instructions he gave his lawyer in preparing the will;
f) the court will interpret the will viewed as a whole (para. 138);
g) the court will prefer an interpretation that leads to a testacy, not an intestacy (para. 139); and,
h) the court will not hesitate to correct obvious mistakes, including deleting or inserting words, where to do so accords with the testator’s intentions, or where not to do so would lead to an absurd result (para 140).
 The proper approach of the court is to consider the language of the will in light of the surrounding circumstances together, rather than one first and then the other: Abram Estate v. Shankoff, 2007 BCSC 1368 at para. 77.