Dylan Pateman, 20, of Station Road, Willoughby admitted driving under the influence of drugs when he appeared at Boston Magistrates Court.
Prosecuting, Lee Shepherd said police were told that the driver of an MG car might be under the influence of drugs and when they saw him in West Street, Alford at around 1am on July 10, he was stopped and provided a positive drugs wipe.
Mr Shepherd said a subsequent analysis revealed a reading of 17 micrograms of cannabis in his bloodstream, the legal limit being two.
He said Pateman told police he had smoked cannabis just an hour before but had received a phone call from a friend asking to be picked up, so he had driven to get him.
Mitigating, Philippa Chatterton said Pateman was a regular user of cannabis and had cooperated throughout.
Pateman was banned from driving for a year and ordered to pay a fine of £120 and court costs and charges totalling £119.