Canabis has no benefit for chronic pain, page-8

Lots of questionable argument.
Professor Michael Farrell said “One of the things we think happens when people report benefits is the sleep and sedation effects it has." “Often when you get a good night’s sleep your pain is a lot more tolerable.”

This statement itself tells me the published results are questionable, the reason you can fell to good sleep only because your pain has been reduced to tolerable so able to falling to sleep otherwise you can't have a good sleep and feel pain being relived. It smell fishing and more like to drive the industry pushing for more funding to "more research is needed".