International Investment Law (IIL), or the international law on foreign investment, deals with the international protection and promotion of foreign investment. Its most important source is the Bilateral Investment Treaty (BIT). BIT is a treaty between two countries aimed at protecting investments made by investors of both countries.1 BITs protect investments by imposing conditions on the regulatory behaviour of the host state and, thus, prevent undue interference with the rights of the foreign investor.2 These conditions include restricting host states from expropriating investments, barring for public interest with adequate compensation and following due process; imposing obligations on host states to accord fair and equitable treatment (FET) to foreign investment and not to discriminate against foreign investment; and allowing for repatriation of profits subject to conditions agreed to between the two countries. BITs also specify what constitutes an ‘investment’ and who qualifies as an ‘investor’. This ensures that BITs protect only such investments and investors. Today, BITs are the most important source of international investment law.3 The first BIT was signed in 1959 between West Germany and Pakistan. As of 2024, the number of BITs is close to 3,000.