Different countries have different laws. In the US there is a 'fair use' exception to copyright. This was always the case, but then the 'digital millennium act' came and made the process of converting a protected media illegal, not the intended use. So while something was considered 'fair use' you were still braking the law by making that copy. Fortunately lawmakers saw the problem and fixed years later. I'm not at all familiar with the laws in the EU and UK, but I would assume what you intend to do with the mp3 makes a big difference.