Giving content to the principle of proportionality: happiness and pain as the universal currency for matching offence seriousness and penalty severity

The principle of proportionality prescribes that the punishment should equal the crime. It is one of the most important principles of sentencing. Yet, despite its widespread acceptance it offers no meaningful guide to sentencing. Hence penalty levels fluctuate greatly between jurisdictions and within jurisdictions. This is because there is no universally agreed criterion for measuring offence seriousness or penalty severity. This article suggests that the appropriate criteria for matching offence seriousness and penalty severity is the level of unhappiness or pain stemming from each of these impositions. Thus, for example, the level of pain meted out to a rape offender should equal the level of pain caused to a rape victim. Emerging scientific studies on human well-being and happiness show that human beings are similarly built in terms of the experiences that are either conducive or inimical to well-being. This commonality provides a strong foundation to be confident to make reasonably accurate predictions concerning the extent to which adverse events, such as being the victim of a criminal offence or subjected to a form of criminal sanction will stifle human flourishing. This will then allow us to match accurately offence seriousness and penalty level.