[A]n alien must establish a clear probability of persecution to avoid deportation under § 243(h).— Immigration and Naturalization Service v. Predrag Stevic, 467 U.S. 407 (1984).
. . .
The principal motivation for the enactment of the Refugee Act of 1980 was a desire to revise and regularize the procedures governing the admission of refugees into the United States. The primary substantive change Congress intended to make under the Refugee Act . . . was to eliminate the piecemeal approach to admission of refuees previously existing under § 203(a)(7) and § 212(d)(5) of the Immigration and Nationality Act, and § 108 of the regulations, and to establish a systematic scheme for admission and resettlement of refugees.
See also Richard A. Boswell's Immigration and Nationality Law: Cases and Materials.