A more thorough explanation:

INS v. Elias-Zacarias is a legal case in which the Supreme Court of the United States decided that a guerrilla organization's attempt to force someone into military service does not necessarily qualify as persecution on account of political opinion under the Immigration and Nationality Act. The Court also established that when determining whether there is persecution on account of political opinion, the court must ascertain the victim's political opinion, not the persecutor's.

For example, in this case, the respondent, Elias-Zacarias, had only been approached by a guerrilla organization once in his home and threatened to join. He did not want to join and was afraid of retaliation, so he fled Guatemala and entered the United States, where he applied for asylum. The Court found that he failed to show that he refused to join because of a political motive. Thus, the focus of the inquiry should be on Respondent's political motive and not the political motive of the persecutors.

The Court also established that a decision by the Board of Immigration Appeals can only be reversed if the evidence presented by the applicant is such that a reasonable fact-finder would conclude that the requisite fear of persecution exists. This means that the applicant must show that there is a "reasonable possibility" that they would be persecuted on account of their political opinion.