Most inquisitors were friars who taught theology and/or law in the universities. They used inquisitorial procedures, a common legal practice adapted from the earlier Ancient Roman court procedures. They judged heresy along with bishops and groups of "assessors" (clergy serving in a role that was roughly analogous to a jury or legal advisers), using the local authorities to establish a tribunal and to prosecute heretics. After 1200, a Grand Inquisitor headed each Inquisition. Grand Inquisitions persisted until the mid 19th century.