A U.S. Supreme Court decision in a synthetic drugs case could help a Duluth head shop owner's appeal of his federal conviction, but state prosecutors say the ruling won't be a factor — for now — in their cases.

In the case, a Charlottesville, Va., man appealed his conviction under the federal Controlled Substance Analogue Enforcement Act. Federal law makes it illegal to knowingly manufacture, distribute or possess controlled substances. In a unanimous ruling written by Justice Clarence Thomas, the court said the law requires prosecutors to prove that the defendant knew he was dealing a controlled substance.

Stephen McFadden was convicted of selling bath salts marketed as "Speed" and "Up" and "Alpha" at his video store, comparing them to cocaine and crystal meth.

The federal threshold for "knowing" is met if the defendant knew the substance was controlled — even if he didn't know what it was — or if he knew the specific features of the substance made it a controlled analogue, the high court said. The 4th Circuit U.S. Court of Appeals didn't accurately convey that requirement in a jury instruction, it said. The matter now goes back to the lower courts to determine whether the error should negate McFadden's conviction.

Defense lawyer Randall Tigue said Thursday that the ruling "makes mincemeat" out of the U.S. attorney's case against James Carlson, owner of the Last Place on Earth shop in Duluth, who was sentenced last year to more than 17 years in prison for selling illegal synthetic drugs designed to mimic the effects of street drugs.

State requirements are different

Those familiar with Minnesota laws said the state doesn't have the same requirements as federal law, so prosecutors' work will remain mostly unchanged.

In Minnesota, "we don't have to prove knowledge of the controlled substance," said Joseph Daly, professor emeritus at Hamline University School of Law in St. Paul. "Knowledge is hard to prove."

Minnesota has worked the past several years to pass laws controlling the sale of high-priced "bath salts" and "incense" that are analogues to street drugs such as cocaine and heroine.

The Duluth case was the most prominent here, but there have been others in state court, as well as deaths from the drugs. Teenagers have been especially vulnerable because of the easier access to the products.

Tigue said the ruling "significantly increases the likelihood" that his client's convictions will be reversed because Carlson didn't meet the threshold for "knowingly" selling the substances. A panel of the Eighth U.S. Circuit Court of Appeals has not yet set a date for a hearing in that case.

U.S. Attorney Andrew Luger's office declined to comment Thursday.

But prosecutors and a law professor said the ruling is unlikely to have much impact on criminal cases in the state's courts.

Assistant Washington County Attorney Fred Fink said the ruling "really has nothing to do with what we do here in Minnesota." Hennepin County Attorney Mike Freeman agreed, saying the number of analogue drug cases his office sees is minimal.

Ruling could shape case law

Ted Sampsell-Jones, a professor at William Mitchell College of Law in St. Paul, said that in the longer term, the ruling could shape case law as courts consider it as guidance. Sampsell-Jones, who has handled many criminal appeals, said the federal case isn't binding in Minnesota but could be "persuasive." He said he expects defense lawyers to refer to it in future cases.

Beyond the courts, however, Minnesota provides other methods of controlling analogue drugs, including the ability of the Minnesota Board of Pharmacy to issue cease-and-desist orders to retailers as well as to engage them in potentially costly litigation.

"Who knows what people who engage in these activities do or think, but they would be pretty dumb to think [the ruling is] going to make it easier to sell synthetic drugs," said Cody Wiberg, executive director of the board. "We have plenty of other tools to prevent those sales."

Rochelle Olson • 612-673-1747

Twitter: @rochelleolson