There's a big fight about whether a criminal should go free because a constable has blundered; e.g., whether the exclusionary rule is the right remedy for police errors. But everyone seems to agree that criminals get to go free when the prosecutor has blundered.
It actually seems to me that not only has the prosecutor blundered, but so has the Legislature. Everyone knows that MDMA ("Ecstasy") is a controlled substance. Yet the relevant Health and Safety Code does not expressly list MDMA as one, and instead simply makes illegal things that are "similar" (isomers of, etc.) to amphetamines. Which Ecstacy is.
The problem is that you need testimony to that effect. Which the prosecutor here didn't elicit. So the only thing we have is (1) common knowledge (which is insufficient for a conviction), and (2) the fact that MDMA is methylenedioxymethamphetamine, which while both relevant and descriptive, isn't sufficient either.
Hence would-be drug dealer Richie Le goes free.