18 U.S.C. § 3126 : US Code - Section 3126: Reports concerning pen registers and trap and trace devices

      The Attorney General shall annually report to Congress on the
    number of pen register orders and orders for trap and trace devices
    applied for by law enforcement agencies of the Department of
    Justice, which report shall include information concerning - 
        (1) the period of interceptions authorized by the order, and
      the number and duration of any extensions of the order;
        (2) the offense specified in the order or application, or
      extension of an order;
        (3) the number of investigations involved;
        (4) the number and nature of the facilities affected; and
        (5) the identity, including district, of the applying
      investigative or law enforcement agency making the application
      and the person authorizing the order.