29 U.S.C. § 2615 : US Code - Section 2615: Prohibited acts

    (a) Interference with rights
      (1) Exercise of rights
        It shall be unlawful for any employer to interfere with,
      restrain, or deny the exercise of or the attempt to exercise, any
      right provided under this subchapter.
      (2) Discrimination
        It shall be unlawful for any employer to discharge or in any
      other manner discriminate against any individual for opposing any
      practice made unlawful by this subchapter.
    (b) Interference with proceedings or inquiries
      It shall be unlawful for any person to discharge or in any other
    manner discriminate against any individual because such individual -
     
        (1) has filed any charge, or has instituted or caused to be
      instituted any proceeding, under or related to this subchapter;
        (2) has given, or is about to give, any information in
      connection with any inquiry or proceeding relating to any right
      provided under this subchapter; or
        (3) has testified, or is about to testify, in any inquiry or
      proceeding relating to any right provided under this subchapter.