Innocent until proven guilty
The legal concept that the guilt of an accused person cannot be presumed and that they must be assumed to be innocent until proven otherwise.
In November 2009, the BBC began televising a courtroom drama series called Garrow's Law. This was inspired by the life of the pioneering 18th century barrister Sir William Garrow. In a broadcast interview about the show, the scriptwriter Tony Marchant was asked by Andrew Marr about a contribution to the language that Garrow is widely reported as making:
Marr: Garrow himself, I think he was the man who coined the phrase 'innocent until proven guilty'.
Marchant: That's right, yes.
Having had a good look into the record books, notably the copious Proceedings of the London Central Criminal Court (The Old Bailey), I can't find any evidence to corroborate that assertion. It is certainly the case that Garrow developed the role of the defence lawyer and championed the notion that every accused person has a right to a defence in which the presumption of innocence is maintained, but it is doubtful that he ever uttered the words 'innocent until proven guilty'. There's no record of it in any of the verbatim reports of the numerous cases that he acted in.
Something he did say, which, in a much more long-winded way, comes to much the same thing was recorded in his defence at the Old Bailey of John Richards and Moses Butler, who were indicted on a charge of burglary in May 1784:
Gentlemen of the Jury, ... whoever is proved to be guilty of that offence, should be brought to the punishment they deserve; but on the other side, it is equally important to justice and humanity, that innocent men should not be fixed with a crime so atrocious in its nature, and so penal in its consequences; in proportion therefore to the malignity of the offence, and the certainty of the punishment that will follow the conviction of it, ought to be the clearness of the evidence by which it is supported, for it would be a dreadful thing on the mind of any humane man, to run any risque of placing an innocent man in that situation, that your verdict must do on conviction ...
The phrase 'innocent until proven guilty' isn't found in print until the 19th century. It appears to be American in origin, as all the early printed citation of it come from there; for example, a plea to a Gettysburg court by a Samuel Chase, reported in the newspaper The Sprig Of Liberty, February 1805:
He wishes the court to consider him innocent until he is proven to be guilty.
The first citation that I can find that refers to the phrase as a legal principle comes from the Law Reports of the Supreme Court of Ohio, 1835:
The law presumes all innocent of crime until proven guilty"