Information and communications technology is a key aspect of a modern, knowledge-based society. Europe-wide millions of people use smartphones on a daily basis for private and business purposes. The importance of smartphones grew with their economic availability, which led to an increased competition between market participants. In the last couple of years powerful, corporate producers of smartphones have been leading a tough competition battle between each other in order to secure a better market position for themselves. In this battle, patents covering the technologies implemented in the products, can be used as a legal instrument, which can hinder the competition and prevent them from entering the market. Especially important in this regard are the so called standard-essential patents (SEP). These are patents which are essential to the implementation of a certain industry standard, which means that the production of standard-compliant products (in this case production of smartphones) is impossible without using the technology covered by SEP. The exercise of exclusive rights based on SEP can potentially amount to an abuse of a dominant market position pursuant to Art 102 TFEU and expose the SEP-owner to the sanctions of the European Commission. In this context, the legal problems arising out of the control of abusive practices according to Art 102 TFEU and maintenance of the effective competition in European single market are the primary research topics of this thesis. After the preliminary introduction into the law concerning the abuse of dominant position according to Art 102 TFEU and its enforcement in accordance with Council Regulation (EC) No 1/2003, the main research is focused on the case analysis of decisions of the EU Commission and of the Court of Justice of EU on the mobile devices market.