Cannabis should be legalised all across the United States, according to a former Supreme Court Justice.

John Paul Stevens, who is 94 years old, has called for the drug to be decriminalised. He claimed the reason was that public opinion on the subject has changed, and that the sacred herb causes leaves less damage in its wake than alcohol.

Stevens used to occupy one of the eight foremost judicial positions in the USA, and appears to have become more radical with old age. He also cited prohibition of alcohol which was made statutory by the Volstead Act in 1919 - and now considered ludicrous.

Stevens has also proposes a ban on capital punishment, as well as a re-wording of the second amendment to make federal gun control more stringent.

Cannabis is currently fully legal in two US states, Colorado and Washington. Following its legalisation in Colorado, the state saw its coffers swell thanks to $2m in marijuana taxes.

Figures reveal the state's 59 marijuana firms made $14m (£8.4m) in gross sales in January, the first month under the new laws.

Colorado legalised cannabis in 2012 but commercial sales did not begin until January, when 24 recreational pot shops were opened.