Derk Pereboom (2014) argues that human beings do not have the kind of free will required for moral responsibility. Pereboom argues that we should use a system of incarceration for criminal offenders based on a quarantine analogy. Patients in quarantine scenarios are not responsible for their sickness, are separated from society because of the danger they pose, and are prepared for release as soon as possible. By analogy, criminal offenders should also be separated from society and rehabilitated to prepare them for release. In this thesis, I extend the ethical applicability of Pereboom’s quarantine system by engaging with an objection from Saul Smilansky. I extend Pereboom’s quarantine system in an additional way by discussing what constraints should be put on the use of direct brain interventions to rehabilitate criminal offenders. In doing so, I start a conversation about how the quarantine system could be implemented in a liberal democratic society.