Two police forces in Maryland — where cannabis is legal for medical and recreational use — are training officers to recognise cannabis impairment.

They posted on Facebook asking for 12 to 14 volunteers over the age of 21 to come along and “smoke cannabis for educational purposes”.

The project “helps both officers and participants better understand the effects and levels of impairment caused by cannabis, all in a safe, controlled setting”, they said.

Within hours, the forces said they had “received an overwhelming number of participant sign-ups and are no longer accepting additional volunteers at this time”.

Participants will have to bring their own cannabis, but will receive a free lunch and a lift home.