Legally, a decision not to prosecute on the basis that no crimes were committed is an exonoration.
Why ? because of the presumption of innocence.
Innocent until proven guilty.
anything else is a corruption of justice
Very true, were France to employ such a legal standard after the revolution Alfred Dryfus would not have spent all that time on Devil's Island. Presumption of Innocence protects the individual in criminal proceedings from the state.