Government says decriminalisation fueled social ills, but producers argue new rules will only push industry underground.

Given that marijuana plants typically run closer to 15 percent THC by dry weight, a 0.3 percent cutoff seemed logical on its face—akin to the 0.5 percent alcohol threshold for nonalcoholic beer.

Neon weed signs have become ubiquitous in Bangkok’s busy tourist areas, with dispensaries cropping up on every corner. Hundreds of food and drink vendors advertise cannabis-infused menus.