swear in (be sworn in)
Definition: to make someone promise to do their duty truthfully either at the beginning of a trial in a court of law or at the beginning of a new official appointment. Usually used in the passive.
E.g.1: The jury was selected and sworn in on Monday and the trial started on Tuesday. The court often swears the jury in the day before the start.
E.g.2: The new President will be sworn in next week.
This phrasal verb can be separated if it is used in the active, but this is unusual. (E.g. 1)