While being caught in possession of the Class B drug can result in a five year prison sentence, police are being advised to walk away even if they strongly suspect someone may have been using the substance.
The official guidance was issued by the College of Policing, which helps formulate the training for all officers in England and Wales.
But last night one of the country's most senior policemen described the guidance as "wrong" and said he would still encourage his officers to carry out stop and search on cannabis suspects.
Chief Constable Andy Cooke of Merseyside Police, wrote on Twitter: "The guidance in my view is wrong and the law does not preclude it .
“Smell of cannabis is sufficient to stop search and I will continue to encourage my officers to use it particularly on those criminals who are engaged in serious and organised crime."
I disagree. The guidance in my view is wrong and the law does not preclude it . Smell of cannabis is sufficient to stop search and I will continue to encourage my Officers to use it particularly on those criminals who are engaged in serious and organised crime. https://t.co/BpUnlJRwDU— Chief Con Andy Cooke (@MerPolChiefCon) 12 December 2017
The controversial guidance appeared in an official College of Policing document, which advises officers against carrying out a stop and search, based solely on the smell of cannabis.
The document recommends that instead of relying on smell alone, an officer should look for other factors to ensure a stop and search is justifiable.
It states: "Other factors could include the person’s behaviour or demeanour, a current drugs marker on the vehicle, specific intelligence about the person or the presence of drugs paraphernalia.
"Officers should consider and record all of the information available to them, including their own observations of suspicious behaviour, not just the smell of what they believe to be cannabis."
Despite the obvious dangers of drug driving, officers are also warned that smelling cannabis in a car is not necessarily justification for searching a vehicle or its occupants.
The guidance also suggests that when using sniffer dogs, a positive reaction by the animal should be treated in the same way as if an officer smells drugs, and therefore should not necessarily be acted upon.
The document states that if officers feel under pressure to respond to public concerns about groups or individuals smelling of cannabis, a stern warning might be better than carrying out a stop and search.
It says: “Where there are insufficient grounds for a lawful search, officers can still take a proactive approach to the public’s concern by reminding the individuals involved that controlled drugs are illegal and that gaining a criminal record may have an impact on their future.”
David Raynes of the National Drug Prevention Alliance said: “This guidance is clearly wrong in law and it is plainly wrong in terms of common sense but police have a problem with small scale drug possession. They have competing priorities and they have to make difficult choices, but this guidance is wrong.”
A spokesman for the College of Policing said while officers and staff were expected to consider the guidance when discharging their duties, there were circumstances when it is “perfectly legitimate” to deviate from it when there was a clear rationale for doing so.
The spokesman for the College of Policing said: “The College of Policing will be reviewing the current stop and search Authorised Professional Practice (APP) regarding the strength of evidence on the smell of cannabis, on its own, as a ground to carry out a drugs search.”
“The review will be taking place to ensure that the national guidance fully reflects the latest research and findings and provides clear information and advice for officers and staff.”