Is a trial judge bound to refrain from participating in the proceedings as to prevent prejudice to the defense?

This court time and again has been confronted with claims that a trial judge has so far injected himself into the proceedings as to have caused prejudice to the defense. Almost as often, it has been held essential that a judge to achieve a fair trial is duty bound to refrain from active participation on one side or the other. See e. g., United States v. Reed,526 F.2d 740, 743 (CA 2 1975), cert. denied, 424 U.S. 956, 96 S.Ct. 1431, 47 L.Ed.2d 361 (1976), and United States v. Curcio, 279 F.2d 681, 682 (CA 2), cert. denied, 364 U.S. 824, 81 S.Ct. 59, 5 L.Ed.2d 52 (1960).

Moreover, a trial judge assuredly is authorized to ask questions which may assist a jury in the evaluation of the nature of the transactions under consideration. United States v. Natale, 526 F.2d 1160, 1170 (CA 2 1975), cert. denied, 425 U.S. 950, 96 S.Ct. 1724, 48 L.Ed.2d 193 (1976).