Hugh Pickens writes "Brandon Keim reports that the war on drugs has a new front, with chemists fabricating synthetic mimics of marijuana, dissociative drugs and stimulants. So far lawmakers appear to be a losing the war, as every time a new compound is banned, overseas chemists synthesize a new version tweaked just enough to evade the letter of the law in a giant game of chemical Whack-a-Mole. 'Manufacturers turn these things around so quickly. One week you'll have a product with compound X, the next week it's compound Y,' says forensic toxicologist Kevin Shanks. 'It's fascinating how fast it can occur, and it's fascinating to see the minute changes in chemical structure they'll come up with. It's similar, but it's different.' During the last several years, the market for legal highs has exploded in North America and Europe. While people raised on Reefer Madness-style exaggerations may be wary of claims that 'legal high' drugs are dangerous, researchers say they're far more potent than the originals. Reports of psychotic episodes following synthetic drug use are common and have led to a variety of laws, but so far the bans aren't working, as the drugs can be subtly tweaked so as to possess a different, legal molecular form. One obvious alternative approach is to ban entire classes of similar compounds; however this is easier said than done. 'The problem with that is, what does "chemically similar" really mean? Change the structure in a small way — move a molecule here, move something to the other side of the molecule — and while I might think it's an analogue, another chemist might disagree,' says Shanks. 'That's the crux of the entire problem. The scientific community does not agree on what "analogue" essentially means.""