It appears that the United Kingdom will exit the European Union as a result of the vote taken in the so-called Brexit referendum. Although the full impact of Brexit is hard to predict, it appears that its effects on United States trade relations may be limited.
Article 50.1 of the Lisbon Treaty provides that any “Member State may decide to withdraw from the Union in accordance with its own constitutional requirements.” Of course, withdrawal is easier said than done. Article 50.2 details the exit procedures which start with a notification by the UK to the EU of its intention to leave the EU. The EU and the UK then, under Article 50.2, negotiate an exit agreement. The exit then becomes effective on the date of the Agreement or after two years, whichever is sooner, unless that period is extended by mutual agreement. Given these provisions, it seems clear that Brexit will be unlikely to take effect until something close to two years from notification at the earliest.
Brexit, even when it becomes effective, will not have an impact on US tariffs on goods imported from the UK. The rates set forth in column 1 of the Harmonized Tariff Schedule, which currently apply to imports from the EU, would continue to apply to products from the UK. The UK is a member of the World Trade Organization, independent of the European Union’s membership, and so the most-favored nation (“MFN”) obligation that the US has with respect to tariffs would continue to apply to the United Kingdom and keep current tariffs in place. (Anti-dumping margins, such as the preliminary margins imposed on March 1, 2016 on cold-rolled steel products from the United Kingdom, would not be affected.)
After Brexit, the United Kingdom would be able to set its own tariffs on imported goods. Whether these tariffs would be greater than those imposed currently by the EU on non-EU products is not certain. The UK will still be bound by its WTO MFN obligations, so it can’t impose higher tariffs on the United States than it imposes on other MFN members. Given this restriction, it seems unlikely that the United Kingdom will significantly raise its tariffs after a Brexit agreement with the EU goes into effect.
Probably the most significant existing trade agreement between the United States and the European Union is the US-EU Air Transport Agreement of April 30, 2007, sometimes called the Open Skies Agreement, which provides, among other things, that all airlines of the parties can obtain landing rights in the territories of the other parties. As with the WTO, the United Kingdom is an independent member of this Agreement along with the EU, so it does not appear that Brexit would affect or require renegotiation of this Agreement.
The most significant prospective agreement with the European Union is the Transatlantic Trade and Investment Partnership (T-TIP). Unlike the Air Transport Agreement, T-TIP would be between the US and the EU alone and not with the individual member states of the EU. (Although the text of any drafts of the T-TIP have not been made publicly available, the negotiations have been between the EU and the US, not with representatives acting on behalf of the UK or any other member state.) Brexit would appear to exclude the UK from participation in T-TIP.
Nigel Farage and other Brexit proponents have stated that Brexit would open up the ability of the United Kingdom to negotiate its own trade agreements with the rest of the world. The extent to which the United States will engage in separate trade negotiations with the UK after Brexit becomes effective over the next two years is unclear.