As of today, possession of cannabis is legal in Canada for the first time since 1923. But there remain major gaps and a lack of consensus around what we actually know in several key areas. The science is far from settled when it comes to cannabis use and its implications for personal health and public health.

In collaboration with the Partnership Group for Science and Engineering (, we have prepared this backgrounder on the health effects and science of cannabis. Feel free to use it and quote from it in your reporting or writing. It is fully referenced and footnoted.