Johns-Manville Canada v. The Queen, 85 DTC 5373, [1985] 2 CTC 111, [1985] 2 S.C.R. 46 -- summary under Improvements v. Repairs or Running Expense

The taxpayer mining company purchased, on an almost annual basis, lands surrounding its open pit mine in order that the perimeter of the sloping sides leading down to the bottom of the pit could be continually expanded through the removal of overburden. The land expenditures were currently deductible partly in light of (1) their recurring nature, (2) the absence of an enduring benefit because similar expenditures were required in the future if the mining operation was to be continued (and the lands were in a sense "consumed") and (3) the fact that they were not made as part of a plan for the assembly of ore bodies or other assets.