... on 3 June 1740, only three days after his father's death, Frederick ordered that torture was no longer to be used, except in a small range of extreme cases involving crimes against king or country, or instances of multiple murder where robust interrogation was required to secure the identity of unknown accomplices. In a further order of 1754, Frederick extended this ban into a blanket prohibition, on the grounds that torture was not only "cruel" (grausam) but also unreliable as a means of getting at the truth, since there was always the danger that suspects would implicate themselves in order to avoid further torture. This radical measure left many judges and legal officials complaining that there now existed no means of extracting a confession -- the queen of proofs under all the ancien regime legal systems -- from recalcitrant offenders. A new evidential doctrine had to be improvised to cover cases where there was a plenitude of evidence, but no confessions.-- Christopher Clark, Iron Kingdom: The Rise and Downfall of Prussia, 1600-1947, p. 253.
... Some reformers today advocate eliminating confessions altogether, since the police have become adept at extracting them without the rack and tongs.