Some scientists have proposed a new classification of drugs according to the level of harm they cause the individual and society. Under the new system, alcohol and tobacco, which are legal drugs, are considered more harmful than cannabis and ecstasy.
The study may be seen by some people as a justification to use drugs that are low down on the "harm scale". Certainly, some readers of this news article about the proposed classification seem to be justifying the use of "less harmful" drugs.
I think the new "league table" plays down the health risks of all of the (legal and illegal) drugs on the scientists' list.