In the United States, in order for a foreign national to qualify as a refugee, he must prove that he meets the definition of the term refugee under the Immigration and Nationality Act (INA). This definition of refugee mirrors the definition adopted in the Refugee Act of 1980 which defines a refugee as a person outside of his country of nationality who is unable or unwilling to return to his country because of persecution or a well-founded fear of persecution on account of race, religion, nationality, membership in a particular social group or political opinion. In some cases, by way of Presidential Determination, some refugees may be processed while still living in their countries of origin. Under U.S. law, any person meeting this definition that has engaged in acts of persecution is not eligible for refugee status. The definition under U.S. law does not include all of the elements of the definition of the term refugee as defined by the United Nations High Commissioner for Refugees (UNHCR), which may include individuals fleeing natural disasters and civil wars. Additionally, in the U.S. the definition of the term refugee excludes so-called "economic migrants" who are fleeing their countries of origin to seek out a more prosperous life. A refugee is distinguished from an asylum seeker in that an individual claiming asylum meets the refugee definition but is already present within the United States or claims asylum at a U.S. port of entry.