The short answer is you don’t.
However, you can nevertheless take actions in response to how their use is affecting you.
There is a lot of controversy around marijuana, especially around potential medical uses of it.
But here are some things we do and don’t know about it.
We do know that marijuana is addictive, and it does have psychotropic properties that impede cognitive and motor functions. The level of addictiveness and degree of impairment is somewhat less than other drugs, but it is nevertheless significant.
There is a lot of information about research done about the addictive nature of marijuana in the Surgeon General’s Report on Alcohol, Drugs and Health. There is a link to this report on the Resources page on this site.
Speaking of research however, the research on medical uses of marijuana is very limited because congress has placed severe restrictions on research of the plant.
There is significant anecdotal evidence, however, of numerous medical benefits of the plant, but research that could back these up is limited. That said, more and more is coming out every day.
The controversy over the potential medical uses of marijuana is also tied up with controversies over the power of pharmaceutical companies in the US in driving research and drug profits, and that’s not something that can be addressed in this workshop.
So, in short, a discussion with your loved one around problems the marijuana use is creating in their life and your relationship, and the degree to which your loved one is showing signs of being addicted, is likely to be more fruitful than a debate on its medical benefits.