There is no doubt that smoking is unlawful, because there are many proofs from the Qur'an and the Sunnah indicating its prohibition. Also, because experts explained that it has negative effects on one's health, finances, and the society. The smoker, seller, and the manufacturer of cigarettes are disobeying Allah and His Messenger. As for the acceptance of a smoker's testimony, it depends upon his situation, the case in which his testimony is required, and the testimony he gives. It is all up to the judge who will hear the case in which the smoker is called to testify.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.