There are two total roles for clerk and bailiff. The clerk role is on prosecution, and the bailiff role is on defense.
The clerk is the time keeper. The Mock Trial Competition has specific allotted times for each section of the trial; going overtime is not allowed. Therefore, the clerk records the times for each part of the trial. They also provide verbal and visual reminders of how much time is left to both teams.
The bailiff is responsible for swearing in witnesses when they are called to testify. They also begin the trial by calling the court to order and introducing the judge.