In the last decade, strong criticism is constantly growing with regard to the International Dispute Settlement Mechanisms (IDSMs) in Trade and Investment disputes.Against this background, the discussion focuses on the search for re-defining the proper balance between IDSMs, states and national courts. To contribute to the ongoing discussion this study explores three main questions.The first question is whether the growing criticism of IDSMs might lead to a greater involvement by national courts in the resolution of investment disputes. To address this, the first chapter explores a judgement by the Israeli High Court of Justice which sets an example of a national court determining the balance between the protection of a foreign investor's rights and a state's freedom to regulate its natural resources.Given that the answer to the first question is, at least to some degree, in the positive, the second question follows as to whether it is legally conceivable that national judicial measures might amount to a violation of the state's international obligations towards a foreign investor, and to a potential state liability in investment arbitration. The second chapter explores the circumstances under which potential state liability might be based on national judicial measures.The third question, explored in the third chapter, adds the dimension of trade by tackling an even greater challenge. It examines the relationship between IDSMs, states and national courts, by offering an analysis of judgments by the Court of Justice of the EU on international trade disputes between the EU and third states that involve political issues related to trade with disputed territories.Given the many challenges relating to re-defining the balance in the relationship between IDSMs, states and national courts, and the expected wider ramifications, the book addresses these issues thoroughly and offers some possible avenues forward.