Aliens — Refugees — Asylum — United Nations Protocol Relating to the Status of Refugees, 1967 — United States Immigration and Nationality Act 1952 — Refugee Act 1980 — Well-founded fear of persecution — Clear probability of persecution — Whether Refugee Act 1980 altering standard applicable to alien already in the United States seeking to resist deportation — Language and legislative history of the Refugee Act 1980 — Whether passed to give effect to the 1967 Protocol — The law of the United States