Courts can both be the subject of public opinion and contribute to its shaping – but incredibly, there have been no observational studies of the persuasive power of courts outside of the United States. In this note, I test whether the UK Supreme Court’s decision that the UK could only leave the EU after parliamentary approval changed
public opinion on this issue. I use data from a two-wave panel, and use coarsened exact matching to compare those who could correctly recall the court’s decision with those who could not. I find that the court’s decision increased support for parliamentary involvement by roughly nine percentage points.