In some jurisdictions, the principle is strictly enforced to avoid any appearance of bias, even when there is none: as Lord Chief Justice Hewart laid down in Rex v. Sussex Justices, "Justice must not only be done, but must also be seen to be done".
In some jurisdictions, the principle is strictly enforced to avoid any perception of bias, even when none exists: as Lord Chief Justice Hewart established in the case of Rex v. Sussex Justices, "Justice must not only be done, but also appear to be done".