Sniffer dogs used to find drugs in police raids or at prisons may be banned from school education visits.
A Norwich Prison sniffer dog detected drugs at a school
A prison drugs dog at Heartsease High school in Norwich during an educational trip set official alarm bells ringing.
Norfolk County Council said they are worried an innocent pupil with traces of relatives' cannabis could be shamed and are reviewing their policy.
Norfolk Police also said officers would not know what to do if a dog found a pupil or teacher possessing drugs.
In 2004 Norfolk police withdrew their own drugs dogs from schools and said it was because there were no clear guidelines, as well as the fact the force's dogs were so popular demand could not be met.
Richard Price, Norfolk Police drugs liaison officer, said: "The kind of incident that could happen would put police officers in a very awkward position and we would seek to avoid that if possible.
"We are looking for clear guidelines and a protocol so that every incidence would be covered."
Many head teachers believe the sessions are important but the possibility of an embarrassing incident is a concern to the county council.
Norwich Prison drugs dogs have detected tens of thousands of pounds worth of drugs in the county in recent years and now its governor has been asked by the council to stop sending the dogs into schools.
The Norfolk Criminal Justice Board said it has not made a final decision to stop using drugs dogs on educational visits.