The Misuse of Drugs Act (1971) and the Psychoactive Substances Act (2016) both reinforce the criminalisation of drug use in the UK. The Psychoactive Substances Act (2016) has been developed to control and monitor the use of legal highs, particularly in institutions. This study aimed to establish drug service providers' viewpoints on how effective UK drug policies have been at curtailing criminal behaviours and whether existing policies should be aligned with the Portuguese drug liberalisation policy. A thematic analysis was conducted following semi-structured interviews with four UK based substance use service providers. Two superordinate themes emerged, (1) the need for change in UK drug policy including a clearer definition of the Psychoactive Substance Act (2016), and (2) an integrated systems approach to drug policy in line with the Portuguese liberalisation policy. This would curtail the criminalization of drug users, target those with substance misuse problems in the community and in prison and support an attuned systems approach to treatment.