With the replacement of Margaret Thatcher in the Prime Ministerial office by John Major, a centrist Tory, Carttiss found himself in conflict with the parliamentary leadership of his party. He was a convinced Eurosceptic and opposed the passage into law through the House of Commons of the Maastricht Treaty, which transformed the European Economic Community into the European Union, and voted against it and his own Party's Government repeatedly in the Commons' division lobby in early 1993.
Upon John Major's succession to the Prime Minister's office, Carttiss clashed with the parliamentary leadership of his party. As a staunch Eurosceptic, he strongly opposed the passage of the Maastricht Treaty through Parliament, which transformed the European Economic Community into the European Union, and repeatedly voted against it and his own Party's Government in the Commons' division lobby in early 1993.