Torture was abolished in England in 1640, in Scotland in 1690, Prussia in 1754, in Denmark in 1770, in Sweden in 1772, in Portugal in 1776, in Italy in 1786, in France in 1789, and even in Czarist Russia in 1801.
As early as 1470, Sir John Fortescue (Henry VI's former chief justice of the King's bench and subsequent chancellor in exile) condemned torture in his De laudibus legum angliae (On the glories of English laws). Comparing the law of England with the laws and procedures of continental legal systems (especially France), Fortescue observed that whereas in England truth in criminal procedures was determined by the deliberation of "twelve good and loyal men," in continental Europe, torture was used to extract confessions from the accused. The trouble was, however, that confessions were not the same as truth: "Such confessions, alas! many ... wretches make, not because of truth, but only because compelled by irresistible torments" (De laudibus, 51).  Fortescue asked, "what man is there so stout or resolute, who has once gone through this horrid trial by torture, be he never so innocent, who will not rather confess himself guilty of all kinds of wickedness, than undergo the like tortures a second time?" He cited the case of a man who, subjected to tortured, falsely accused a "man of worth and loyalty"; it was only as he was about to expire that the poor bastard cleared the man, adding that to avoid the same terrible torture he would have accused his own father.  A century after Fortescue, Sir Thomas Smith argued that torture was unacceptable because if a man was subsequently acquitted, "what amends can be made him?" Smith also argued that information obtained under toture was valueless, as men would say anything to be released from pain, and a jury, out of pity, would acquit a man who had been so abused. 
In a seminal essay on torture published in 1764, Cesare Beccaria argued that "this abuse should not be tolerated in the eighteenth century" because it inflicted "infamy" on its victims and because it often convicted the innocent:
"No man can be considered guilty before the judge has reached a verdict, nor can society deprive him of public protection until it has been established that he has violated the pacts that granted him such protection. What right, then, other than that of force, can empower the judge to inflict punishment on a citizen while his guilt or innocence remains in doubt? This dilemma is not new: either the crime is certain or it is not; if certain, no punishment awaits him other than that which has been established by the laws, and torture is useless because the criminal's confession is useless; if it is not certain, the one must not torture an innocent man, because in the eyes of the law he is a man whose crimes have not been proven. But I shall add something more: it is a wilful confusion of the relationships between cause and effect to require that a man be at once accuser and accused, and that pain should be made the crucible of truth, as if the criterion of truth lay in the muscles and fibres of a poor wretch. This is a sure way to acquit the robust criminals and to convict the innocent who are weak.
Speaking the truth in the midst of spasms and agony is as little a free action as was in an earlier era to thwart the effects of fire and boiling water without recourse to trickery. Every act of our will is always proportional to the force of the sensory impress from which it spring; and the sensory capacity of every man is limited. Therefore, the impression of pain may increase to such a degree that, filling the entire sensory capacity, it leaves the torture victims no liberty but to choose the shortest route to relieve his pain momentarily. Under these circumstances, the statements made by the accused are as inevitable as the impression made by fire and water. And thus the innocent and sentient man will declare himself guilty if he thinks that doing so will make the pain cease. All differences between the guilty and the innocent disappear as a consequence of the use of the very means ostensibly employed to discover them. It would be redundant to cast further light on this by citing the unnumerable examples of innocent men who confessed their guilt amid the spasms inflicted by torture; there is no nation and there is no age that cannot cite its own examples, but men neither change nor draw conclusions from these cases.
The outcome of torture, therefore, is a matter of temperament and calculation, which varies with each man according to his sturdiness and sensibility, so that, with this method, a mathematician would solve the following problem better than a judge could: given the strength of an innocent's man's muscles and the sensitivity of his fibres, one need only to find the degree of pain that will make him confess his guilt for a given crime.
Lastly, torture is applied to the accused in order to discover his accomplishes in crime; but if it has been demonstrated that torture is not an effective means to discover the truth, how can it serve to reveal the accomplices, which is one of the truths to be discovered? As if the man who accuses himself will not more readily accuse others." 
Beccaria's book On Crimes and Punishments was much lauded by Enlightenment luminaries in Europe and North America. Beccaria argued for equality of every citizen before the law, the right to a fair trial, the abolition of the death penalty, and the elimination of the use of torture in criminal interrogations.
 Barbara Hanawalt, David Wallace, Medieval Crime and Social Control, U of Minnesota Press, 1999, p. 91.
 John Fortescue, De Laudibus Legum Angliae (1775), Andrew Amos trans., Cambridge, 1825, p. 72. Available for download from Google Book here.
 John Bellamy, The Tudor Law of Treason: An Introduction, Routledge, 1930, p. 110.
 Cesare Beccaria, On Crimes and Punishments and Other Writings, Aaron Thomas and Jeremy Parzen trans., University of Toronto Press, 2008, pp. 32-37.