The British recently INCREASED it’s illegality (to class B, stuff like crack is class A) after finally accepting the wealth of medical advice that habitual use of today’s stronger weed significantly increases the risk of chronic mental disorders, particularly if smoked from before one’s mid-20s.
As to supposed medical benefits, there are none – I refer you to the biggest review of its kind, in the Pain Physician journal, Sept 2017 (of which the pdf is free online) “Efficacy of Cannabis-Based Medicines for Pain Management: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.” This looked at 43 – FORTY THREE – randomized clinical trials and found most of them found MJ showed absolutely no benefits over placebo, let alone even trying to see if they can out-do any established pain killers.