Lateral support describes the right of land to the support of the land lying next to it, so that a neighbor's land will provide support against any slippage, cave-in or landslide. The right to lateral support is absolute with regard to land in its natural condition. Therefore, courts apply a strict liability standard when an adjoining landowner interferes with this right. When improvements on the land have suffered a loss of support, however, courts differ in how they modify the standard of liability. In lateral support cases involving improvements, courts have limited the strict liability standard by first deciding whether the improvements contributed to or caused the subsidence and then applying strict liability only if the land would have subsided without the improvement.
Should the adjoining owner excavate into the soil for any reason (foundation, basement, leveling) then there must be a retaining wall constructed (or other protective engineering) to prevent a collapse. The most common need for lateral support is in the construction of deep basement excavations.
