This WAW panel will focus on how unilateral acts have emerged as a source of international law. It will also analyze how an investment law may constitute a basis for consent to investor-State arbitration, and how, notwithstanding this possibility, and the practice of non-treaty and non-contract cases. In particular, this panel will discuss: The most recent developments regarding investment laws as bases for consent to international investment arbitration How the language of the relevant law may provide for ICSID arbitration? and Whether and under what conditions a host State may withdraw its consent given through a domestic law to ICSID arbitration