The government's attempt to ban "legal highs" could criminalise priests who use incense during services, churches have warned.
The Psychoactive Substances Bill will seek to ban to substances with a broad definition so as to keep up with the fast-changing range of new legal substances that arrive in Britain.
It is so broad it could prohibit the use of incense in associations, according to the Churches’ Legislation Advisory Service (CLAS), a charity that represents religious institutions, and the Association of English Cathedrals.
The CLAS quoted Lord Howarth of Newport, who told the House of Lords: “We do not want to criminalise priests. The more vigorously the priest swings the censer, the more incense is let loose into the body of the church."
"We entirely understand why that should be so: that a detailed description of each banned substance would mean that they could be reformulated with a slightly changed molecular structure in order to get around the legislation," Frank Cranmer, CLAS secretary, wrote to parliament's Home Affairs Select Committee.
"Nevertheless, a problem remains for the Churches that use incense in their worship (and, for that matter, for other religious communities such as Hindus and Buddhists): that under the Bill as currently drafted it would be of doubtful legality."
He added: "We cannot for one moment believe that is the intention of the Government to make the use of incense in religious worship illegal. We would urge that, for the avoidance of doubt, a specific exemption for the use of incense in places of worship be inserted."
When Lord Howarth raised the concern about incense in the Lords, Lord Bates said, on the government's behalf: "It is not accidental that we have drawn this widely; it was deliberately done to recognise that there is a particular problem here."
The Home Affairs Select Committee is conducting an inquiry into psychoactive substances.
Metropolitan Police officer Simon Bray, the national police lead on psychoactive substances, told the committee he was relaxed about what the broadness of the definition would mean for enforcement.
"I am aware of the debate around the term 'psychoactivity'," he said. "We are confident that the definition has worked elsewhere in other jurisdictions, so we will work very closely with them.
"What we are after, of course, is something that is as clear as possible for police officers and law enforcement to operate and for the public to understand."