CONCORD, N.H. — The New Hampshire Supreme Court says a police officer who stopped a driver for a defective headlight acted unlawfully when he asked to see the driver’s tongue and then used its green hue as the basis for a marijuana arrest.

The court reversed the drug convictions of Hillman Blesdell-Moore, saying the Enfield officer who stopped him had no basis to ask to see his tongue and continue questioning him about whether a drug-sniffing dog might be alerted to his pickup truck.

In a unanimous decision Tuesday, the justices said Officer Roy Holland’s request to see the driver’s tongue transformed the routine traffic stop in November 2011 into an unconstitutional search for evidence of drug possession.

The court says all drug evidence stemming from the stop should have been suppressed at trial.