Someone asked a lawfag to post about the empaneling of a Grand Jury? For starters, go here https:// www.law.cornell.edu/rules/frcrmp/rule_6). The text of the quote is too long to post here, but this will get you started:
'''Rule 6. The Grand Jury
(a) Summoning a Grand Jury.
(1) In General. When the public interest so requires, the court must order that one or more grand juries be summoned. A grand jury must have 16 to 23 members, and the court must order that enough legally qualified persons be summoned to meet this requirement.
(2) Alternate Jurors. When a grand jury is selected, the court may also select alternate jurors. Alternate jurors must have the same qualifications and be selected in the same manner as any other juror. Alternate jurors replace jurors in the same sequence in which the alternates were selected. An alternate juror who replaces a juror is subject to the same challenges, takes the same oath, and has the same authority as the other jurors.
(b) Objection to the Grand Jury or to a Grand Juror.
(1) Challenges. Either the government or a defendant may challenge the grand jury on the ground that it was not lawfully drawn, summoned, or selected, and may challenge an individual juror on the ground that the juror is not legally qualified.'''