Mixed legal systems have traditionally been classified as such by reference to varying degrees of ‘mixité’ within areas of private law. This paper refocuses such long-established methods of classification by considering the mixedness of public law, and moves discussion to systems where new mixes are taking place, particularly in the context of the European Union. The author analyses the changing composition of the new mixed systems, and characterises the processes of transposition and cross-fertilisation by which they have been reached.