Soliciting or Providing Testimony Outside Judicial Role: Frequently, when judges see there are big holes in a case, they will simply find a way to get the testimony in that is necessary to throw it in the direction of the particular litigant they've decided will win.
In my case, I recall the judge asking my ex's attorney questions about some retirement accounts in my ex's name thus cluing the attorney in on what arguments to use to get my ex excused from the penalties he should have endured for not reporting them on his financial agreement.
In Kathi Sorrentino's case, the judge intervened extensively and simply elicited the testimony he wanted to get out of Mr. Sorrentino, rather that leaving it up to the attorneys to argue to argue their case. If you have the judge inserting evidence into the case of his own volition, and disregarding his role as neutral decision maker, how can you possibly believe that you have a fair trial.
For instance, at one point while examining Mr. Sorrentino on the stand, Kathi Sorrentino was able to point out that he had no evidentiary basis for his accusations. Immediately, Judge Corinne Klatt rushed to his rescue stating, "Well, ma'am, to be quite frank, that -- those comments are stricken. You want to know why? Because I am the one who determines credibility, not you."