Elphicke campaigned to remain in the European Union in the 2016 membership referendum. He contributed to the Conservative Government's first defeat over key Brexit legislation in December 2017, when he abstained in the vote on Dominic Grieve's amendment requiring Parliament to have a vote on the final deal relating to the UK departing the European Union. Elphicke argued in the House of Commons that the process of taking back control from the EU should be carried out in a manner that respected the sovereignty of Parliament.