The British government announced today it is to toughen the laws on cannabis use.
Home Secretary Jacqui Smith said the drug must be upgraded from Class C to Class B to avoid "risking the future health of young people".
The move comes despite the Advisory Council on the Misuse of Drugs (ACMD) concluding that the health dangers from cannabis did not justify its inclusion in the higher category.
A report from the group said scientific evidence pointed to a "probable, but weak, causal link between psychotic illness, including schizophrenia, and cannabis use".
However, in the population as a whole, the drug played only a "modest role" in the development of these conditions, it said.