Legality of Kratom in the UK From the 2016 psychoactive substances act. It appears that possession unless in a custodial premises (this must mean prison right?) is in fact legal. So once it's in your hands it is not an offence? I've always been told it is illegal to possess in the UK completely. This suggests otherwise. The act: makes it an offence to produce, supply, offer to supply, possess with intent to supply, possess on custodial premises, import or export psychoactive substances; that i