Once a judge has allowed expert evidence to be admitted at trial, is the Court’s “gatekeeper function” at an end? A recent decision of the Ontario Court of Appeal, Bruff-Murphy v. Gunawardena, 2017 ONCA 502, establishes that where an expert’s testimony leads to questions about her impartiality at trial, the trial judge has a positive and ongoing duty to exclude the evidence or give a warning to the jury, even after the evidence has been admitted.