Guarantees of origin are tradeable energy certificates defined by directives 2009/28/EC and 2018/2001/EU of the European Union. They serve the aim of informing final consumers on energy sources used for their electricity supply. They are also expected to encourage new investments in renewable electricity generation. This paper investigates how the use of guarantees of origin meets these expectations. A literature review, an analysis of related regulations and an evaluation of empirical data shows that there are regulatory failures both at national and the European Union levels. Furthermore, due to a contradiction between certain rules in European Union level regulation, consumers receive unreliable information on their electricity consumption mix. Therefore, although national rules should be improved, the problem of reliability cannot be resolved until the Union level framework is modified. Furthermore, the present framework does not incentivise investments in renewable energy technologies either. Accordingly, recommendations are formulated for policy makers to ensure reliable and sufficient operation of the certificate system.