"Because of health concerns and the abuse potential of herbal incense products, many have been banned in several European countries, 18 U.S. states, and the U.S. military.33,38 In March 2011, the FDA placed 5 synthetic cannabinoids (JWH-018, JWH-073, JWH-200, CP-47,497, and cannabicyclohexanol) on Schedule I, making them illegal to possess or sell in the United States.38"

Source

Pierre, Joseph M., "Cannabis, synthetic cannabinoids, and psychosis risk: What the evidence says," Current Psychiatry (Parsippany, NJ: September 2011) Vol. 10, No. 9, p. 56.