After release from prison or a custodial preventive institution, offenders may come under supervision in Germany, which means that their conduct is controlled for a period of up to five years or even for life by a judicial supervising authority. Supervision is terminated if it can be expected that even in the absence of further supervision the released person will not commit any further offences. From the theoretical point of view, supervision is not considered a form of punishment in Germany, but a preventive measure that is guided by the principle of proportionality. After a presentation of the German twin track system of criminal sanctions and a glimpse at sentencing theory, the capacity of the principle of proportionality to guide and control judicial decisions in the field of preventive sanctions is discussed. The human rights perspective plays only a minor role in the context of supervision in Germany.

In the Netherlands, the legal possibilities for post-custodial supervision have been extended considerably in recent years. A currently passed law aims to further increase these possibilities specifically for dangerous (sex) offenders. This law consists of three separate parts that may all result in life-long supervision. In the first two parts, the supervision is embedded in the conditional release after either a prison sentence or the safety measure ‘ter beschikking stelling’ (TBS). This paper focuses on the third part of the law, which introduces an independent supervisory safety measure as a preventive continuation of both a prison sentence and the TBS measure. Inevitably, this new independent sanction raises questions about legitimacy and necessity, on which this paper reflects from a human rights perspective. Against the background of the existing Dutch penal law system, the content of the law is thoroughly assessed in view of the legal framework of the Council of Europe and the legal principles of proportionality and less restrictive means. In the end, we conclude that the supervisory safety measure is not legitimate nor necessary (yet). Apart from the current lack of (empirical evidence of) necessity, we state that there is a real possibility of an infringement of Article 5(4) ECHR and Article 7 ECHR, a lack of legitimising supervision ‘gaps’ in the existing penal law system, and finally a lack of clear legal criteria. Regardless of the potential severity of violent (sex) offenses, to simply justify this supervisory safety measure on the basis of ‘better safe than sorry’ is not enough.