MINNEAPOLIS — A federal judge on Tuesday denied a motion for a new trial or acquittal for a Duluth head shop owner and two employees convicted in a major synthetic drug case.

U.S. District Judge David Doty wrote that the evidence presented at trial was “more than sufficient” to support the convictions of Jim Carlson, his girlfriend and Carlson’s son. The judge also rejected defense claims that he made errors in the jury instructions and improperly prevented the defense from introducing statements by public officials as evidence on why the defendants believed their actions were legal.

Carlson defiantly ran the Last Place on Earth, which did a brisk business in synthetic marijuana and other substances before authorities shut the shop down in July after a long fight. He was taken into custody shortly after a jury convicted him in October on 51 felony counts that included dealing in misbranded drugs and conspiracy.

Carlson’s attorney, Randall Tigue, said the decision was not unexpected given several recent rulings in favor of the government. He said the defendants will raise the same issues with an appeals court.

“These are issues of first impression and the judge made no attempt to consider the merits,” Tigue said. “We will look forward to getting a court that will actually do that.”

Doty signed an order last week allowing the federal government to seize Carlson’s money and property once he is sentenced. His sentencing date has not been set.

The jury also convicted Carlson’s girlfriend, Lava Haugen, on four counts, and his son, Joseph Gellerman, on two counts.