The introduction of the Diplock court system in Northern Ireland in 1973 was attended with much controversy. Established to deal more effectively with terrorism without using internment, in a Diplock court, defendants are tried for serious criminal offenses by a judge alone, rather than by a jury. The authors of this article conducted a 12-month study, observing jury and nonjury trials in Belfast Crown Court, where Diplock trials are held. The study's objective was to test in a systematic way over a number of trials whether the Diplock procedure has moved away from the conventional hallmarks of the classic adversarial trial in the direction of a more inquest-oriented procedure. The specific hallmark discussed in this article is the role of the judge, i.e., are Diplock judges to adopt the conventional neutral umpire type of role, or are they to attempt to shed more light in cases by asking questions to satisfy themselves of the truth, thereby running the risk that intervention may be seen as one-sidedness? Results of the study revealed that there is a greater overall quantity of interventionism in Diplock trials and differences in the timing of questions, but relatively little difference in terms of the types of questions asked. There, however, was a great variation in individual judicial conduct of trials. The authors conclude that within the Diplock structure there is at least the potential for the presentation of the defense to be prejudiced by excessive judicial intrusion.