Van Son Estate v. The Queen, 90 DTC 6183, [1990] 1 CTC 182 (FCTD) -- summary under Subsection 70(6)

The deceased taxpayer bequeath his 49% shareholding in a private company to his surviving wife. Joyal J. found that under a buy-sell agreement of the taxpayer with the majority shareholder, there was an obligation imposed on the majority shareholder to buy the estate's shares on the taxpayer's death, but there is no obligation on the estate to sell those shares. Because on the taxpayer's death the shares were not subject to an obligation to sell, the indefeasible vesting requirement was met.