“… in N.W.L. Ltd. v. Woods [1979] I.C.R. 867, 880, Lord Diplock said that a judge ought to "give full weight to all the practical realities of the situation to which the injunction will apply" and that the American Cyanamid decision "was not dealing with a case in which the grant or refusal of an injunction at that stage would, in effect, dispose of the action finally in favour of whichever party was successful in the application, because there would be nothing left on which it was in the unsuccessful party's interest to proceed to trial." Lord Diplock continued: "Cases of this kind are exceptional, but when they do occur they bring into the balance of convenience an important additional element." …. If it will not be possible to hold a trial before the period for which the plaintiff claims to be entitled to an injunction has expired, or substantially expired, it seems to me that justice requires some consideration as to whether the plaintiff would be likely to succeed at a trial. In those circumstances it is not enough to decide merely that there is a serious issue to be tried. The assertion of such an issue should not operate as a lettre de cachet, by which the defendant is prevented from doing that which, as it later turns out, he has a perfect right to do, for the whole or substantially the whole of the period in question. On a wider view of the balance of convenience it may still be right to impose such a restraint, but not unless there has been some assessment of the plaintiff's prospects of success. I would emphasise "some assessment," because the courts constantly seek to discourage prolonged interlocutory battles on affidavit evidence. I do not doubt that Lord Diplock, in enunciating the American Cyanamid doctrine, had in mind what its effect would be in that respect. Where an assessment of the prospects of success is required, it is for the judge to control its extent”