The courts of England and Wales are headed by the Lord Chief Justice of England and Wales; in Northern Ireland's courts, the equivalent position is the Lord Chief Justice of Northern Ireland, and in the courts of Scotland the head of the judiciary of Scotland is the Lord President of the Court of Session, who is also Lord Justice General of Scotland.
These three judges are not, though, part of the Supreme Court of the United Kingdom, which operates across all three jurisdictions and is headed by the President of the Supreme Court of the United Kingdom.
In several countries, the chief justice is second in line to the office of president or governor general (or third in line, if there is a vice president or lieutenant governor general), should the incumbent die or resign.
For example, if the Governor General of Canada is unable to perform the duties of the office, the Chief Justice of Canada performs the duties of the governor general.
Apart from their intrinsic role in litigation, they may have additional responsibilities, such as swearing in high officers of state; for instance, the Chief Justice of the United States traditionally administers the oath of office at the inauguration ceremony of the President of the United States, as does the Chief Justice of South Africa at the inauguration of the President of South Africa.