What is the effect of the Courts of Equity’s jurisdiction on the terms of a personal injury agreement?

Viscount Haldane, in Drinkle v. Steedman (1916) 1915 CanLII 426 (UK JCPC), 9 WWR 1146, at 1148, [1916] 1 AC 275, 85 LJPC 79, 33 WLR 483, 25 DLR 420, reversing (1914) 1913 CanLII 192 (SK CA), 5 WWR 706, 7 Sask LR 20,14 DLR 835, states to the same effect, the full quotation being: “ * * * Courts of Equity,: which look at the substance as distinguished from the letter of agreements, no doubt exercise an extensive jurisdiction which enables them to decree specific performance in cases where justice requires it, even though literal terms of stipulation as to time have not been observed. But they never exercise this jurisdiction where the parties have expressly intimated in their agreement that it is not to apply, by providing that time is to be of the essence of their bargain. If, indeed, the parties, having originally so provided, have expressly or by implication waived the provision made, the jurisdiction will again attach.”