The presumption of innocence is a cornerstone of the American legal system and a foundational principle of criminal law procedures. This presumption shifts the burden of proof onto the prosecution to affirmatively prove that you committed the criminal act. This has several ramifications that may not be apparent at first glance.
First, it means that you won't be constantly harassed by the state filing criminal charges against you that required you to prove your innocence. Without the presumption of innocence, there would be little to prevent the state from charging you with crimes and forcing you to constantly prove your innocence. With the presumption in place, the state has an incentive to only bring charges against those it actually believes committed a crime.
Second, it means you don't have to say a single thing, or prove a single thing in your defense. You could be silent the entire trial and put on no defense whatsoever, and unless the prosecution can prove that you committed the crime, you should be judged not guilty.
See Defending Yourself Against a Criminal Charge for more information about the prosecution's burden of guilt and defendants' presumption of innocence.
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