Modern scholarly tradition has established that two fundamental rules regulated the use of torture in ancient Rome: torture must not be applied to Roman citizens or to slaves against their owners. It is commonly thought that during the Republic these principles were breached but exceptionally, whereas under the Empire their violation became ever more frequent as the extraordinary cognitiones invaded the criminal procedure. Expansion of torture has been associated with the political interests of imperial regime inaugurated by Augustus that took increasingly inquisitive and harsh measures against those convicted, or even suspected, of threatening the well-being of the Emperors and the Empire. The torture spread slowly but gradually to investigation of wider range of crimes, until the generalization of its use at the latest under the Severan emperors. The progress of torture during the first two centuries of the Empire is not, however, without contradiction, as scholars note the legal doctrine prohibiting the torture of freemen was duly maintained. Yet it is often taken for granted that at least the underprivileged inhabitants of the Roman Empire, the so-called humiliores in the legal jargon, in practice, if not in theory, lost protection against torture.