The topic of pharmaceutical, biological and chemical patents is a special matter within European and German patent law. Structural alternations give rise to the question under what circumstances they can be novel and in which cases they are included under state of the art. But even if a substance is prior art, a new medical use of it can be patented, as such medical use patents are politically intended to promote medical research. On the other hand, it is unclear how to deal with natural occurrences of a substance in terms of its accessibility an bioethics. It must also be understood how different identifications of a substance and the resulting patents interrelate with each other, i.e. how their scopes of protections are defined. This is problematic especially because of the absolute substance of protection, which includes all conceivable uses and methods. The past decisions of the ECJ as regards broccoli-and-tomato-patents, as well as embryonic stem cells have highlighted the importance of this field of law.