Attorneys for John Sdao's family say the 20-year-old died in 2012 after using a product called Spice. It was purchased at a Royal Oak gas station.
Trial began Monday in Oakland County Circuit Court in Pontiac.
Spice is a mix of dried herbs and spices sprayed with chemicals. It has been blamed for health problems and violent behavior, especially among young people.
Michigan banned synthetic marijuana in 2012, a few months after Sdao's death.