Actually THE STATE presumes him guilty and tries to show that in a court of law. The court presumes him innocent and THE STATE can not deprive him of his liberty or property unless THE STATE can prove beyond a reasonable doubt to triers of fact, jury or judge as the case may be, that he is guilty of something.
The court is an agent of the state. The state acts as both the prosecuter and the trier, though they are separate agencies of the state.