Montgomery County Police Station in Maryland invited legal cannabis users to light up in front of officers so they could see the effects first-hand, The Times reports.

Cannabis is legal in Maryland when prescribed by medical practitioners, and the state will hold a referendum on full legalisation in November this year.

Members of the public attending the pot parties had to bring their own cannabis but were supplied with drinks, snacks and pizza by supportive police officers and dropped off at home afterwards.

The force is now likely to organise further parties — with one participant suggesting that the impaired smokers could drive go-karts to test their driving ability.

The participant said: “That’s what they do with alcohol. They said: ‘You want to come again and do the go-karting track?’ I thought: ‘You want me to smoke cannabis and drive go-karts? Yeah. I will come. I’m looking forward to it.”