What is the test for determining whether there has been or not enough publicity to prevent a fair trial?

What must be shown is a high probability that the effect of publicity will be to leave potential jurors so irreparably prejudiced or to so impair the presumption of innocence that a fair trial is impossible. That conclusion does not necessarily flow from proof that there has been or will be a great deal of publicity about the ITOs. Evidence of the probable effects is required. Accused persons enjoy the right to a fair trial, not the right to be free from excessive adverse publicity before his or her trial. Negative publicity alone does not preclude a fair trial. While the nexus between publicity and its lasting effects is not susceptible of scientific proof, the focus must be on that link, not the mere existence of publicity. Any alleged impartiality of jurors can only be measured in the context of the safeguards which have evolved in order to prevent such problems. Re Phillips v. Nova Scotia (Westray Inquiry) (1995), 1995 CanLII 86 (SCC), 98 C.C.C. (3d) 20 (S.C.C.), at paras. 128-130.