Lateral Support of Land. Ardavicius v. Kairys
In Ardavicius v. Kairys (Div Ct, 2009) the Divisional Court held that adjoining landowners owe each other a duty of 'lateral support' with respect to each other's land, which is sometimes characterized as an easement. The result is that any actions by one which negatively effect the lateral support of the land of the other give rise to liability, whether it be characterized as nuisance, trespass or negligence:
The right to lateral support of abutting land
 The trial judge found that the plaintiff was entitled to recover the cost of building a retaining wall which she was required to construct due to the appellants’ undermining of the support to her property.
 The following are the relevant findings of fact and law of the trial judge:
I conclude that the defendants are liable to the plaintiff in nuisance, negligence, and trespass for causing the loss of support, undermining, and seepage of earth necessitating the building of the retaining wall. The first wall wasn’t very effective. I award $6300.00 against the defendants I award no damages for stress. There is a short letter from a family physician, but this aspect was not fully developed. Litigation in itself is stressful. As noted above, the appellants argued that recovery for loss of support is barred where the plaintiff’s land is not in its natural state. I would dismiss this ground of appeal.
The case of Monroe v. Emerson is applicable 1992 CanLii 838 (B.C. S.C.). In that case the slope of land was also from the plaintiff’s property to the defendant’s. The defendant excavated on their lands causing an even steeper slope. Wetmore J. stated at page 2 of the report as follows:
The law is clear that an owner of land has an easement of what is usually called lateral support to the boundaries of his property to the extent that the natural state of the land adjoining provided. The removal of that support becomes actionable when damage occurs to the dominant lands…
The court awarded as damages the cost of the building a retaining wall.
In the case of Masciolli v. Betteridge et al. 1965 CanLII 231 (ON SC),  1 O.R. 627 per Moorehouse J. a similar conclusion was reached, but on the basis of nuisance. At page 3 of the Quicklaw report there is a quotation from a decision of Schroeder J. as follows:
Broadly speaking, nuisance is a wrong done to a man by unlawfully disturbing him in the enjoyment of his property, and the wrong is in some aspects analogous to trespass.
At page 5 of the report there is a quotation from Watson B.
The same rules of law apply in such a case as to the right of lateral support of adjoining land, which is not an easement. If by digging, the adjoining land is let down, the right of compensation is on the ground that the adjoining owner could not use his own land to the prejudice of his neighbour, not on the ground of disturbance of an easement.
As mentioned above liability of the defendants in this case can also be founded on the basis of negligence and trespass.
 Firstly, if the appellants wished to make this argument, they should have done so before the trial judge. The cases referred to by the appellants involve situations where the nature of the land, and whether it was in a natural state, was a clear issue in the trial.
 Secondly, there was sufficient evidence before Winer D.J. to find that the plaintiff’s land was in its natural state. The plaintiff testified that her property was as she had purchased it in 1986. The trial judge accepted the plaintiff’s evidence.
 Since there was evidence to support the conclusion that the land of the plaintiff was in its natural state, the respondent had a right of support as an incident of her property right, and no easement was necessary. Loss of the right is actionable in nuisance: Anne Warner La Forest, Anger & Honsberger Law of Real Property, looseleaf, 3d ed., (Toronto: Canada Law Book, 2008) at §17.20.40(a); Mascioli v. Betteridge-Smith Construction Co. Ltd., 1965 CanLII 231 (ON SC),  1 O.R. 627-636 (H.C.J.); Boyd v. Toronto (City),  O.J. No. 143, 23 O.L.R. 421 (H.C.J. (Div. Ct.); Hunt v. Peake (1860), 70 E.R. 603 (Q.B.).
 The trial judge reached his conclusions based first on the loss of lateral support caused by the appellants’ actions, but also reached the same conclusions with respect to the remedies of negligence or trespass. These alternative conclusions are also supported by the evidence.