evidence: A provisional agreement was approved by the U.K. parliament on Jan. 1, 2021. It was approved by the European Parliament on April 28, 2021. While the deal, known as the Trade and Cooperation Agreement (TCA), allowed tariff- and quota-free trade in goods, U.K.-EU trade still faces customs checks. This means that commerce is not as smooth as when the U.K. was a member of the EU. [...] The new Withdrawal Agreement replaced the controversial Irish backstop provision with a protocol. According to the revised deal, the entire U.K. left the EU customs union upon Brexit, but Northern Ireland continued following EU regulations and value-added tax (VAT) laws for goods, while the U.K. government collected the VAT on behalf of the EU. [...] Negotiators in the U.K. and EU worried about the consequences of reinstating border controls, as Britain had to do in order to end freedom of movement from the EU. Yet leaving the customs union without imposing customs checks at the Northern Irish border or between Northern Ireland and the rest of Britain left the door wide open for smuggling. This significant and unique challenge was one of the reasons soft Brexit advocates cited in favor of staying in the EU’s customs union and perhaps its single market.