A more thorough explanation:

Definition: An ex officio justice is a judge who serves on a commission or board only because the law requires the presence of a judge rather than because the judge was selected for the position.

Example: In some states, the chief justice of the state supreme court serves as an ex officio member of the state's Judicial Council. This means that the chief justice is required to serve on the council because of their position as chief justice, not because they were chosen specifically for the council.

Explanation: The example illustrates the definition of an ex officio justice because the chief justice is not selected for the Judicial Council based on their qualifications or experience, but rather because the law requires a judge to be present on the council. The chief justice serves on the council as an ex officio member because of their position as chief justice.