The principle of in dubio pro reo (Latin for "when in doubt, for the accused") means that a defendant may not be convicted by the court when doubts about his or her guilt remain.
It is often used specifically to refer to the rule of interpretation that dictates that when a criminal statute allows more than one interpretation, the one that favours the defendant should be chosen.[1]
The principle is not normalized in the German law, but is derived from Article 103(2) GG, Article 6 ECHR, as well as § 261 Code of Criminal Procedure. The principle has constitutional status.
The main principle in the sentence was part of Aristotle's interpretation of the law and shaped the Roman law. However, it was not spelled out word for word until the Milanese jurist Egidio Bossi (1487–1546) related it in his treatises. The common use of the phrase in the German legal tradition was documented in 1631 by Friedrich Spee von Langenfeld.