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In many places in the country, you can legally buy a drug meant to get you high. It's called spice, and sometimes K2 or spike. States have tried to ban and regulate it, but it's tricky because the drug is synthetic. California outlawed some ingredients, but then the drug-makers tweaked their formula. Now San Diego is trying a new tactic. As Claire Trageser from member station KPBS reports, the city's trying to outlaw the drug's effects rather than its chemical makeup.
CLAIRE TRAGESER, BYLINE: Pictures of brightly colored packages with names like fruit punch, the joker and OMG are spread out on a table. Their shiny wrappers are decorated with cartoon characters.
KATHRYN TURNER: They look more like candy.
TRAGESER: Kathryn Turner is a San Diego city attorney. She's showing examples of the drug spice that undercover police officers bought legally over the counter.
TURNER: The spice packages are sold as potpourri, but very expensive potpourri.
TRAGESER: At $15 a pack, this so-called potpourri can be smoked to mimic marijuana's high. In 2011, California banned the compounds used to make spice.
TURNER: So the chemist - and I've described them as evil chemists - just slightly change the molecular architecture of these compounds.
TRAGESER: These changes mean the drug still gets you high, but now is legal again. And because the chemicals keep changing, there's no way to completely predict how the body will respond to them. Sometimes that means seizures, comas and hallucinations.
More than 500 people in San Diego were hospitalized for bad spice reactions in the past six months, up from around 100 in the six months before. Now the city is following other states such as Rhode Island and Florida by banning not just specific chemicals used to make spice, but any compound that produces a similar reaction in the brain.
JERRY YANG: I would just take some of this solution out.
TRAGESER: Jerry Yang is a chemist at UC, San Diego. He pulls from a shelf in his lab a glass tray of 96 tiny test tubes. He explains how they're used to test if a new spice is similar to the old version.
YANG: And at the end, I just measure how much color is actually being generated. It sounds comically simple.
TRAGESER: The test is easy, but Yang says what's tough is where to draw the line.
YANG: So how are you going to manage that? Are you going to screen every product in the world and figure out its biological response and then set limits based on what you learn?
TRAGESER: He worries about broadening the ban too much.
YANG: And so now if you ban anything that elicits a response, how are you going to manage banning things that we didn't intend to ban?
MARGARET DOOLEY-SAMMULI: It's 2016, not 1970. We know that banning a drug doesn't make it go away.
TRAGESER: Margaret Dooley-Sammuli is the policy director of the San Diego ACLU. She also worries the ban could be too broad. And she doesn't think making the sale of spice illegal will stop people from taking it.
DOOLEY-SAMMULI: Unfortunately, it means that people who use it will end up in jail at a taxpayer cost of over a hundred dollars a day and where there is no drug treatment, by the way.
TRAGESER: But allowing spice to be sold legally isn't the solution, says city attorney Kathryn Turner. And, she argues, this new law will end the cat-and-mouse game.
TURNER: And just talk about what is it doing to the human body, and then protecting people here in the city of San Diego from being that human guinea pig.
TRAGESER: Because with spice, users never know exactly what they're smoking. For NPR News, I'm Claire Trageser in San Diego. Transcript provided by NPR, Copyright NPR.