"common law says that every person is innocent till proven guilty.'
The presumption of innocence, an ancient tenet of Criminal Law, is actually a misnomer. According to the U.S. Supreme Court, the presumption of the innocence of a criminal defendant is best described as an assumption of innocence that is indulged in the absence of contrary evidence (Taylor v. Kentucky, 436 U.S. 478, 98 S. Ct. 1930, 56 L. Ed. 2d 468 ). It is not considered evidence of the defendant's innocence, and it does not require that a mandatory inference favorable to the defendant be drawn from any facts in evidence.
Here is Bob Klitzkie's more lengthy and scholarly treatment of this issue. Please, people on our side, read up so you don't sound as stupid as The Ric.