In the United States the law requires that the prosecutor prove the guilt of each defendant at trial by a beyond a reasonable doubt standard. This means that the prosecutor must prove each element of each charge. The defendant need not prove his innocense but the prosecutor must prove guilt. For each criminal statute the statute itself or the courts have delineated certain elements that must be proved by the state. For the most part states are free to designate what elements must be proved prior to a person being found guilty of a particular offense.
One element of most offenses is called the mens rea. The mens rea is the state of mind that one must have to commit an offense. Prior to 2002, the law in Florida required that to convict a defendant of a drug offense a mens rea of knowledge was necessary. In other words the state was required to prove that the defendant knew that he/she possessed a substance and that he/she knew that the substance was illegal. In 2002 the legislature passed an act specifically deleting any requirement that a person know the illegal nature of the substance. Thus if someone gives you a white chrystaline substance and tells you it is sugar. You believe the person and you prepare to sweeten your coffee with it. But the police come to your house with a search warrant and seize the substance which later tests positive for cocaine you are guilty of possession of cocaine.
Under the law if you go into court and you prove that you thought the substance was sugar you may be found not guilty. But the burden of proof is on you, not the prosecutor to prove that you thought the substance was sugar. This is called an affirmative defense.
Mackle Vincent Shelton was sentenced to eighteen years in prison for conviction, among other things of delivery of cocaine. He filed a writ of habeas corpus in Federal Court challenging the lack of a mens rea requirement. The District Court granted his writ but the Eleventh Circuit Court of Appeals reinstated his conviction.
The trial court instructed the jury that Shelton could be found guilty of delivery of cocaine if the state proved “ [t]hat Mackle Vincent Shelton delivered a certain substance; and,  [t]hat the substance was cocaine.” In his petition Shelton claimed that the lack of a mens rea requirement violated the due process clauses of the Fourteenth Amendment.
As in the Ninth Circuit’s Frost case the issue was not whether or not the statute violated the Constitution but rather whether or not the Court, in giving the instruction, violated a Supreme Court decision. Since the Supreme Court has never held that there must be an mens rea requirement 1 in a drug case the Eleventh Circuit reversed the District Court and reinstated the conviction.
- Nor has it ever stated that that a perrson can be convicted without a mens rea instruction. ↩