The First Department, in a full-fledged opinion by Justice Andrias, determined that the participation of the judge in the questioning of witnesses did not rise to the level of depriving the defendant of a fair trial:
The guarantee of a fair trial does not “inhibit a Trial Judge from assuming an active role in the resolution of the truth” … . Thus, a trial judge is permitted “to question witnesses to clarify testimony and to facilitate the progress of the trial,” and, if necessary, to develop factual information … . However, a judge may not “take  on either the function or appearance of an advocate at trial” … .
The “substance and not the number of questions asked is the important consideration” … . Even if a trial judge makes intrusive remarks that would better have been left unsaid, or questions witnesses extensively, the defendant is not thereby deprived of a fair trial so long as the jury is “not prevented from arriving at an impartial judgment on the merits” … . Notably, although the exercise of a trial court’s power to question witnesses should be exercised “sparingly” …, “in the case of expert testimony, the court’s intervention is often necessary to assist the jurors in comprehending matters of specialized knowledge” … , and the trial judge is afforded greater leeway.
The record before us establishes that the trial court did not take on the function and appearance of an advocate. * * *
Furthermore, although it is true that a “claim that the intrusion of the Trial Judge deprived [the defendant] of his constitutional right to a fair trial is not subject to harmless error analysis” …, the strength or weakness of the evidence may be considered as a factor in determining whether the defendant received a fair trial … . People v Adams, 2014 NY Slip Op 02349, 1st Dept 4-3-14