What is the standard of proof in para. 7?

The proposition in para. 7 is taken from Vout v. Hay, supra, at para. 24 of Sopinka J's. reasons: [page447] With respect to the first problem, in accordance with the general rule applicable in civil cases, it has now been established that the civil standard of proof on a balance of probabilities applies. The evidence must, however, be scrutinized in accordance with the gravity of the suspicion. As stated by Ritchie J. in Re Martin; MacGregor v. Ryan, 1965 CanLII 17 (SCC), [1965] S.C.R. 757, at p. 766: The extent of the proof required is proportionate to the gravity of the suspicion and the degree of suspicion varies with the circumstances of each case.