Torts - Nuisance - Private
Damages - Difficulty of Proof
TMS Lighting Ltd. v. KJS Transport Inc. (Ont CA, 2014)
In this case the Court of Appeal engaged in a review of the doctrine of private nuisance, with particular attention to the the issue of abnormal sensitivity of the plaintiff. The fact situation was airborne dust infiltration from a neighbouring manufacturer. The Court reviewed and characterized the case doctrine as follows:
 To begin, the trial judge recognized the two-part test for establishing private nuisance and the factors relevant to the assessment of the reasonableness of an unauthorized interference with private property rights, as set out in Antrim Truck Centre Ltd. v. Ontario (Transportation), 2011 ONCA 419 (CanLII), 2011 ONCA 419, aff’d 2013 SCC 13 (CanLII), 2013 SCC 13. See also, Mandrake Management Consultants Ltd. v. Toronto Transit Commission, reflex,  O.J. No. 995, 102 D.L.R. (4th) 12 (Ont. C.A.).The court also considered the doctrine applicable to the quantification of damages where they were inherently difficult to prove, and commented on this issue as follows:
 Antrim confirms, at para. 18, that private nuisance consists of an interference with a plaintiff’s use or enjoyment of land that is both substantial and unreasonable. The Supreme Court explained, at para. 19:
A substantial interference with property is one that is non-trivial. Where this threshold is met, the inquiry proceeds to the reasonableness analysis, which is concerned with whether the non-trivial interference was also unreasonable in all of the circumstances. With respect to the reasonableness component of the test for private nuisance, the Antrim court emphasized, at para. 25, that the reasonableness of the interference must be assessed in light of all the relevant circumstances. Further, under the reasonableness inquiry, the court assesses, “in broad terms, whether the interference is unreasonable by balancing the gravity of the harm against the utility of the defendant’s conduct in all of the circumstances”: Antrim at para. 26. While the courts are not limited by any specific list of factors in assessing the gravity of the harm occasioned by the defendant, such factors as the severity of the interference, the character of the neighbourhood, the sensitivity of the plaintiff to the harm caused, and the frequency and duration of the interference may be relevant under the reasonableness inquiry: Antrim at paras. 26 and 53-54.
 At the outset, I acknowledge that a trial judge’s assessment of damages attracts considerable deference from a reviewing court. Appellate interference with a damages award at trial, particularly an award made by a trial judge sitting alone, is justified only where the trial judge made an error in principle, misapprehended the evidence, failed to consider relevant factors, considered irrelevant factors, made an award without any evidentiary foundation, or otherwise made a wholly erroneous assessment of damages: Kerr v. Baranow, 2011 SCC 10 (CanLII), 2011 SCC 10,  1 S.C.R. 269, at para. 158; Magnussen Furniture Inc. (c.o.b. Magnussen/Presidential Furniture) v. Mylex Ltd., 2008 ONCA 186 (CanLII), 2008 ONCA 186, 89 O.R. (3d) 401, at para. 71; Naylor Group Inc. v. Ellis-Don Construction Ltd., 2001 SCC 58 (CanLII), 2001 SCC 58,  2 S.C.R. 943, at para. 80.
 It is also beyond controversy that a plaintiff bears the onus of proving his or her claimed loss and the quantum of associated damages on a reasonable preponderance of credible evidence. Further, as the trial judge recognized in this case, a trial judge is obliged to do his or her best to assess the damages suffered by a plaintiff on the available evidence even where difficulties in the quantification of damages render a precise mathematical calculation of a plaintiff’s loss uncertain or impossible. Mathematical exactitude in the calculation of damages is neither necessary nor realistic in many cases. The controlling principles were clearly expressed by Finlayson J.A. of this court in Martin v. Goldfarb, 1998 CanLII 4150 (ON CA),  O.J. No. 3403, 112 O.A.C. 138, at para. 75, leave to appeal to S.C.C. refused,  S.C.C.A. No. 516:
I have concluded that it is a well established principle that where damages in a particular case are by their inherent nature difficult to assess, the court must do the best it can in the circumstances. That is not to say, however, that a litigant is relieved of his or her duty to prove the facts upon which the damages are estimated. The distinction drawn in the various authorities, as I see it, is that where the assessment is difficult because of the nature of the damage proved, the difficulty of assessment is no ground for refusing substantial damages even to the point of resorting to guess work. However, where the absence of evidence makes it impossible to assess damages, the litigant is entitled to nominal damages at best.See also Cadbury Schweppes Inc. v. FBI Foods Ltd., 1999 CanLII 705 (SCC),  1 S.C.R. 142, at para. 99; 100 Main Street East Ltd. v. W.B. Construction Ltd. 1978 CanLII 1630 (ON CA), (1978), 20 O.R. (2d) 401 (C.A.), 88 D.L.R. (3d) 1, at para. 80; Penvidic Contracting Co. v. International Nickel Co. of Canada, 1975 CanLII 6 (SCC),  1 S.C.R. 267, at pp. 278-79.
 Thus, the respondents bore the onus of establishing their lost productivity damages, which they characterized in their pleading as “special damages”. Whether damages of this type are properly to be termed “special damages” (a label that I regard as inappropriate), or simply as a type of general damages to be measured in accordance with the trial evidence, the plaintiff bears the onus of proof on a balance of probabilities.
 On this appeal hearing, the respondents do not fault the trial judge for rejecting their theory of the appropriate method for the calculation of lost productivity damages in nuisance. Rightly so. There was no evidence at trial to support the respondents’ proposed use of a range of two to seven percent of gross sales revenues to measure these damages. As a result, consistent with his obligations under Goldfarb and related cases, the trial judge was obliged to examine whether the evidentiary record afforded a reasonable and reliable alternative basis for the quantification of these damages.
 The quantification of damages occasioned by a proven loss is often a difficult task. In many cases, while loss is established, the evidence affords little support for a precise or reliable assessment of damages arising from the loss. For this reason, as Finlayson J.A. noted in Goldfarb, at para. 75, a trial judge confronted with a meagre evidentiary record on damages may be required to resort to educated “guess work”.
 That said, in my opinion, it is not open to a trial judge to postulate a method for the quantification of damages that is not supported by the evidence at trial. Nor is it open to a trial judge to employ an approach to the quantification of damages that the parties did not advance and had no opportunity to test or challenge at trial. See for example, Stemeroff v. Swartz, 2005 CanLII 18183 (ON CA),  O.J. No. 2073, 198 O.A.C. 141 (C.A.); and, in the context of liability, Rodaro v. Royal Bank of Canada, 2002 CanLII 41834 (ON CA),  O.J. No. 1365, 59 O.R. (3d) 74 (C.A.). To hold otherwise would sanction trial unfairness.