This thesis deals with the major legal issues of the gas pipeline embargo. It is not an abstract treatise on extraterritoriality under international law, but a legal expertise on the legality of the unique measures imposed in 1982. It also tries to point out the legal trends as indicated by the recent publications. The first part of the thesis examines to what extent some European firms were affected by the American embargo. The second part examines whether the President had the authority under the Export Administration Act of 1979 to impose the far-reaching extraterritorial restrictions. It concludes that the President enacted some of the controls without authorization by the Act. The next part deals with the issue whether the export restrictions, although not authorized by the Act, can be upheld by the inherent powers of the President. It concludes that the restrictions could not have been imposed legally based on the inherent powers of the President. The fourth part then deals with the question whether the export restrictions violated the Constitution. It states that the Constitution did not limit the power of Congress or the President in this particular case. The final part shows the issues of international law involved in the gas pipeline embargo. It focuses on the question of extraterritorial jurisdiction of states. The examination points out that the extraterritorial controls cannot be based on generally accepted bases of jurisdiction and violated the sovereign rights of the affected European states. The conclusion summarizes the results of the thesis.