What Happens When a Conviction May Have Rested on a Legally Inadequate Theory ?
In Griffin v. United States, 502 U.S. 46, 116 L. Ed. 2d 371, 112 S. Ct. 466 (1991), the Supreme Court clarified that the Yates rule did not apply when the alternative ground was legally proper but failed because of insufficient evidence. See also San Martin v. State, 717 So.2d 462, 470 (Fla. 1998) ("While a general guilty verdict must be set aside where the conviction may have rested on an unconstitutional ground or a legally inadequate theory, reversal is not warranted where the general verdict could have rested upon a theory of liability without adequate evidentiary support when there was an alternative theory of guilt for which the evidence was sufficient.").
The Griffin court explained the distinction between a legally inadequate theory and a factually insufficient theory:
Jurors are not generally equipped to determine whether a particular theory of conviction submitted to them is contrary to law--whether, for example, the action in question is protected by the Constitution, is time barred, or fails to come within the statutory definition of the crime.
When, therefore, jurors have been left the option of relying upon a legally inadequate theory, there is no reason to think that their own intelligence and expertise will save them from that error.
Quite the opposite is true, however, when they have been left the option of relying upon a factually inadequate theory, since jurors are well equipped to analyze the evidence, see Duncan v. Louisiana, 391 U.S. 145, 157, 20 L. Ed. 2d 491, 88 S. Ct. 1444 (1968).
As the Seventh Circuit has put it:
It is one thing to negate a verdict that, while supported by evidence, may have been based on an erroneous view of the law; it is another to do so merely on the chance--remote, it seems to us--that the jury convicted on a ground that was not supported by adequate evidence when there existed alternative grounds for which the evidence was sufficient. United States v. Townsend, 924 F.2d 1385, 1414 ([7th Cir.] 1991) Griffin, 502 U.S. at 59-60.