January 24, 2020 – The Law of Mistake

“To the extent that Susan is seeking to vary paragraph (h) of the Gilmore Order, there are no grounds to support such a request.  As stated, the Gilmore Order is a consent order.  The jurisprudence is clear that a consent order may only be set aside or varied on the grounds of common mistake, misrepresentation, fraud or any other ground which would invalidate a contract.

As held by the Court of Appeal for Ontario in Miller Paving Ltd. v. B. Gottardo Construction Ltd. 2007 ONCA 422 (CanLII), in order to find the presence of common mistake, the following elements must be proven:

(a)    a common assumption as to the existence as to the state of affairs;

(b)    no warranty by either party that the state of affairs exists;

(c)    the non-existence of the state of affairs must not be attributable to the fault of either party;

(d)    the non-existence of the state of affairs must render performance of the contract impossible: and

(e)    the state of affairs may be the existence, or a vital attribute, of the consideration to be provided or circumstances which must subsist if performance of the contractual adventure is to be possible.”

Vasarhelyiv v. Borges, 2019 ONSC 590 (CanLII) at 18-19