For companies engaged in the international trade of goods or services, the decision of the United Kingdom to exit from the European Union, creates uncertainty on many levels. Laying aside political effects, such as potential reconsideration of Scotland’s 2014 decision to remain in the U.K. (Scotland having overwhelmingly voted to stay in the U.K. during the Brexit referendum), the legal issues stemming from the Brexit decision are almost too numerous to mention.  But, for a U.S. company thinking through the implications of Brexit, resultant changes in treaty obligations, British law, and U.S. law are the major categories to monitor carefully.