The U.S. Supreme Court case Immigration and Naturalization Service v. Cardoza-Fonseca in 1986 revolved around the interpretation of a provision in the Immigration and Nationality Act regarding asylum seekers. The respondent, Cardoza-Fonseca, was a Nicaraguan citizen who had entered the United States illegally but sought to avoid deportation by applying for asylum on grounds that she feared persecution if returned to her home country. The INS denied her application because they believed she failed to prove "a clear probability of persecution," which is required for withholding deportation under Section 243(h) of the act. However, Cardoza-Fonseca argued that this standard was too high for an asylum claim under Section 208(a), which only requires demonstrating a "well-founded fear" of persecution - not necessarily proving it's highly likely or probable. In its decision, the Supreme Court sided with Cardoza-Fonseca (7-2 majority), ruling that these two standards were indeed different: while withholding deportation demands proof of likely persecution, obtaining asylum merely needs credible evidence suggesting reasonable fear thereof.

In the dissenting opinion for Immigration and Naturalization Service v. Cardoza-Fonseca, Justice Powell argued that the majority's interpretation of "well-founded fear" in asylum cases was too broad and would potentially allow any alien to claim a subjective fear of persecution. He contended that this could lead to an influx of immigrants claiming asylum based on fears not grounded in reality or probability. Furthermore, he disagreed with the majority's decision to separate the standards for withholding deportation from those governing asylum applications, arguing it created unnecessary confusion and complexity within immigration law. Justice Powell believed there should be a single standard - requiring clear probability of persecution - applicable both for granting asylum and withholding deportation.