The burden is always on the prosecution to prove the guilt of the accused beyond a reasonable doubt before a conviction can be had.20

But when the defendant sets up an affirmative defense, such as alibi, insanity, or self defense, the burden is on him to establish it by such weight of evidence as, when considered with all the other evidence, raises a reasonable doubt of his guilt.21

But in some jurisdictions the burden is on the accused to establish his defense of alibi, insanity, or self-defense by a preponderance of the evidence,*22 and in some states, beyond a reasonable doubt.23