(a) This chapter applies, according to the provisions thereof, except to the extent that-
(1) statutes preclude judicial review; or
(2) agency action is committed to agency discretion by law.
(b) For the purpose of this chapter-
(1) "agency" means each authority of the Government of the United States, whether or not it is within or subject to review by another agency, but does not include-
(A) the Congress;
(B) the courts of the United States;
(C) the governments of the territories or possessions of the United States;
(D) the government of the District of Columbia;
(E) agencies composed of representatives of the parties or of representatives of organizations of the parties to the disputes determined by them;
(F) courts martial and military commissions;
(G) military authority exercised in the field in time of war or in occupied territory; or
(H) functions conferred by sections 1738, 1739, 1743, and 1744 of title 12; subchapter II of chapter 471 of title 49; or sections 1884, 1891-1902, and former section 1641(b)(2),of title 50, appendix; 1 and
(2) "person", "rule", "order", "license", "sanction", "relief", and "agency action" have the meanings given them by section 551 of this title.