As spoke of in the writings of Johannes Trithemius, Abbott of Sponnheim, stories of the Court of the Holy Vehm or the Secret Society of Judges were told. It was backed by the Holy Roman Emperor at times, and founded by Charlemagne. I'm unsure as to if this is what (s)he was talking about, however, it seemed fitting to me after reading about it. Usually, the vehmic court would perform on an ad-hoc basis; usually to protect the 10 commandments. Most of the members swore a vow to eradicate heresy, traitors, lawbreakers, and uphold the 10 commandments. If anyone was found guilty, the punishment was most likely death via a multitude of creative ways such as stabbing with a cruciform dagger, or lead sprinkling. Usually, these acts were committed at night; with every member wearing a cloak of black. They would capture people by finding them on roads at night, and if they defended themselves, they would die by stabbing. If they didn't, they would have a hood placed over their head and taken to a remote location under a midnight sky facing the judges, and a sentence would be passed. Again, if found guilty, they would die. Most of this information is acquired from the writings of Johannes Trithemius, as well as Philip Schaff's A religious Encyclopedia, or definition of Biblical, Historical, Doctrinal, and Practical Theology vol. 3 on page 2451.