This chapter holds that the CJEU follows two diametrically diverging doctrines regarding the relationship between international and EU, as well as EU and Member State law. From a theoretical perspective this is inconceivable. One and the same organization cannot follow two different approaches. However, from a pragmatic perspective, this chapter acknowledges that this Janus face of the CJEU is quite understandable. Autonomy understood as monism, on the one hand, is an expression of legal unity, which is absolutely necessary for the EU to safeguard its integration process. On the other hand, autonomy expressed as dualism helps to secure the stability of this integration process by separating the EU legal order from far-reaching international influences. However, at the same time, autonomy cannot provide for an adequate replacement of monism and dualism.