The government of Sweden encourage the development of electricity produced from renewable sources by maintaining an electricity certificates system in which producers that use renewable sources in their production are given certificates. The system is regulated in the Swedish Electricity Certificates Act (lag (2003:113) om elcertifikat). To prevent fraudulent behaviour a penalty fee is charged upon producers that have recieved certificates due to incorrect or misleading information. The penalty fee can be appealed to a court but under the Electricity Certificates Act it is not allowed to reduce or adjust. The purpose of this thesis is to analyse if the penalty fee in the Electricity Certificates Act meets the requirements of legal certainty in article 6 of the European Convention on Human Rights (the Convention) including right to a fair trial and to be seen as innocence until proven guilty. The method used is analysing applicable sources in accordance with the Swedish legal hierarchy in which laws have the highest value. The Convention is incorporated into Swedish law and has the same legal value as such. Judgments from the European Court of Human Rights on the Swedish tax surcharge are used for guidance on how to interpret article 6 in the Convention. Two cases from Swedish courts concerning the penalty fee are used to find what problems the penalty fee encounters in a legal process. The rules on the penalty fee does not allow adjustments of it and circumstances in each case cannot be taken into consideration, therefore the penalty fee can be charged even when it would be unreasonable and there is a conflict with legal certainty in article 6 of the Convention. For that matter rules on evidentiary issues also has to be implemented. Courts can refuse to use rules which are in conflict with the Convention, but it is concluded that a change in regulation is needed.