The article analyzes two cases when Germany became part of investment arbitration in ICSID. In both cases Swedish energy company Vattenfall was claimant. But if the first arbitration the German government was brought to court for actions of a regional government, in the second case it was due to its own decision on accelerated nuclear phase-out. The decision as of 2011 was taken in short time and without discussing with business reps what led to significant infringement of rights of the nuclear industry. At the same time an application of a Swedish company to ICSID against a EU member state entailed a counteraction of EU Comission which decided to join the arbitration as amicus curiae. Ultimately the effectiveness of ICSID arbitration for Vattenfall can be considered as positive. In the first case the parties reached an amicable settlement, and in the second a similar outcome can be expected due to favorable decision of the German constitutional court on obligation of fair and just compensation. It can be said that the ICSID arbitration proceeding alone helps the company to achieve desired outcome in negotiations with government authorities as a political tool.