Principle of proportionality as a threat to criminal-law-related fundamental rights

The article argues that the principle of proportionality—a legal tool widely used for balancing competing rights—can be perceived as a threat to criminal-law-related fundamental rights, i.e. mainly the nullum crimen sine lege and ne bis in idem principles. A case study is carried out, of A and B v Norway, Tsonyo Tsonev v Bulgaria (no 4) and Saquetti Iglesias v Spain ECtHR judgments, as well as P16-2021-001 ECtHR advisory opinion and Menci CJEU ruling, heavily relying on the rule-principle distinction (as presented by Ronald Dworkin and Robert Alexy). The conclusion stemming from the study can be described as follows: in some instances ‘inserting’ proportionality into the content of fundamental rights might be inappropriate, i.e. dogmatically flawed and detrimental to the effective protection of these rights.