15.—(1) A person who, when driving or attempting to drive a mechanically propelled vehicle on a road or other public place, is unfit to drive through drink or drugs is guilty of an offence.
(2) Without prejudice to paragraph (1), a person who, when in charge of a mechanically propelled vehicle which is on a road or other public place, is unfit to drive through drink or drugs is guilty of an offence.
(3) For the purposes of paragraph (2), a person shall be deemed not to have been in charge of a mechanically propelled vehicle if he proves that at the material time the circumstances were such that there was no likelihood of his driving it so long as he remained unfit to drive through drink or drugs.
(4) The court may, in determining whether there was such a likelihood as is mentioned in paragraph (3), disregard any injury to him and any damage to the vehicle.
(5) For the purpose of this Article, a person shall be taken to be unfit to drive if his ability to drive properly is for the time being impaired.
(6) A constable may arrest a person without warrant if he has reasonable cause to suspect that that person is or has been committing an offence under this Article.
(7) For the purpose of arresting a person under the power conferred by paragraph (6), a constable may enter (if need be by force) any place where that person is or where the constable, with reasonable cause, suspects him to be.