28 U.S.C. § 2201 : US Code - Section 2201: Creation of remedy

      (a) In a case of actual controversy within its jurisdiction,
    except with respect to Federal taxes other than actions brought
    under section 7428 of the Internal Revenue Code of 1986, a
    proceeding under section 505 or 1146 of title 11, or in any civil
    action involving an antidumping or countervailing duty proceeding
    regarding a class or kind of merchandise of a free trade area
    country (as defined in section 516A(f)(10) of the Tariff Act of
    1930), as determined by the administering authority, any court of
    the United States, upon the filing of an appropriate pleading, may
    declare the rights and other legal relations of any interested
    party seeking such declaration, whether or not further relief is or
    could be sought. Any such declaration shall have the force and
    effect of a final judgment or decree and shall be reviewable as
    such.
      (b) For limitations on actions brought with respect to drug
    patents see section 505 or 512 of the Federal Food, Drug, and
    Cosmetic Act, or section 351 of the Public Health Service Act.