Whoever attempts to influence the action or decision of any grand
or petit juror of any court of the United States upon any issue or
matter pending before such juror, or before the jury of which he is
a member, or pertaining to his duties, by writing or sending to him
any written communication, in relation to such issue or matter,
shall be fined under this title or imprisoned not more than six
months, or both.
Nothing in this section shall be construed to prohibit the
communication of a request to appear before the grand jury.