… the Germanic, fundamental principle of evidence in criminal cases. That proceeds from the idea that establishing the truth concerning a committed crime has of course to draw on sources revealing their history, such as the statements of witnesses, circumstantial evidence, etc., but that indeed the main point, the criminal's guilt, being a purely inward matter, can only be established by an inward method. We must refer to the treatises cited above for how this view was expressed even in the earliest, crude systems of evidence (with oath-helpers, duel, and ordeals), naive and barbaric though they were.

The system of jurors arose gradually from the oath-helpers of the accuser…. The fact, precisely, that the system of jurors arose from oath-helpers explains: why in England the twelve jurors have to be unanimous, for otherwise the charge or the evidence would not have been conducted through twelve oath-helpers; and why they (the jurors) are not tied to any rules of evidence but have to follow solely the voice of their conscience, for, as with the oath-helpers of former times, everything depends on their opinion, on their conviction. That is how the number of the jurors is to be explained: twelve, which was very customary also for oath-helpers; and why the jurors are judges only of the fact, and not also of the law, which indeed was similarly foreign to the consideration of the oath-helpers….