Applicants for certificates also had to convince the police that they had a good reason for needing a certificate. The law did not affect smooth-bore guns, which were available for purchase without any form of paperwork. The penalty for violating the Act was a fine of up to £50 or "imprisonment with or without hard labour for a term not exceeding three months", or both. The right of individuals to bear arms had previously been, in the words of the 1689 Bill of Rights, "as allowed by law". The 1920 Act made this right conditional upon the Home Secretary and the police. A series of classified Home Office directives defined for the benefit of chief constables what constituted good reason to grant a certificate. They originally included self-defence. As the 1920 Act did not prevent criminals from obtaining firearms illegally, in 1933 the Firearms and Imitation Firearms (Criminal Use) Bill was submitted to Parliament. It increased the punishment for the use of a gun in the commission of a crime and made it an offence punishable by up to 14 years' imprisonment for anyone to "attempt to make use" of any firearm or imitation firearm to resist arrest. Possession of a real or imitation firearm was also made an offence unless the possessor could show he had it for "a lawful object". The Firearms Act 1937 incorporated various modifications to the 1920 Act based on the recommendations of a 1934 committee chaired by Sir Archibald Bodkin. The resulting legislation raised the minimum age for buying a firearm or airgun from 14 to 17, extended controls to shotguns and other smooth-bore weapons with barrels shorter than (later raised by the Firearms Act 1968 to , transferred certificates for machine guns to military oversight, regulated gun dealers, and granted chief constables the power to add conditions to individual Firearms Certificates. The same year, the Home Secretary ruled that self-defence was no longer a suitable reason for applying for a firearm certificate and directed police to refuse such applications on the grounds that "firearms cannot be regarded as a suitable means of protection and may be a source of danger". The Firearms Act 1968 brought together all existing firearms legislation in a single statute. Disregarding minor changes, it formed the legal basis for British firearms control policy until the Firearms (Amendment) Act 1988 was put through Parliament in the aftermath of the 1987 Hungerford massacre. For the first time, it introduced controls for long-barrelled shotguns, in the form of Shotgun Certificates that, like Firearm Certificates, were issued by an area's chief constable in England, Scotland, and Wales.