One of the most striking developments in the penal system in England and Wales is the increasing use of the polygraph by probation services. Despite severe criticism from scientific institutions and academic discourse, the legal order increasingly deploys the long-discredited polygraph in order to extract adverse statements from released offenders. Our article is structured as follows: First, we summarise the statutory and regulatory framework for the current use of the polygraph in the monitoring of sex offenders released on licence, and the proposed expansion of the polygraph testing regime as set out in the Domestic Abuse Bill and the Counter-Terrorism and Sentencing Bill respectively. We then review our findings in respect of governing policies and procedures uncovered by our FOI-based research, highlighting the concerning lack of consistency in respect of both practice and procedure. In the subsequent sections we set out the main arguments deployed by polygraph proponents, and posit our view that none of these arguments can withstand scrutiny. We conclude by proposing a moratorium on any further use of the polygraph by the State, in order to thoroughly evaluate its effect on the integrity of the legal order, human rights and, more generally, the Rationalist aspirations of the penal system. In addition, and given already existing law, we propose a process of independent oversight and scrutiny of the use of the polygraph in licence recall decisions and other situations impacting individual rights, especially police investigations triggered by polygraph test results.