What are the principles of judicial decorum, and what are the consequences of a judge's actions and comments at trial?

In conducting trials, judges "`should be exceedingly discreet in what they say and do in the presence of a jury lest they seem to lean toward or lend their influence to one side of the other.' [Citation.]" {People v. Sturm (2006) 37 Cal.4th 1218, 1237-1238, 39 Cal.Rptr.3d 799, 129 P.3d 10.) Their conduct must "`"accord with recognized principles of judicial decorum consistent with the presentation of a case in an atmosphere of fairness and impartiality[.]" '" (Hernandez v. Paicius (2003) 109 Cal.App.4th 452, 462, 134 Cal. Rptr.2d 756.) "`The trial of a case should not only be fair in fact, ... it should also appear to be fair.'" (Id at p. 455, 134 Cal.Rptr.2d 756.) The judge's actions and comments during trial violated these principles such that "`it shocks the judicial instinct to allow the judgment to stand.' [Citation.]" (Ibid.)