T he Immigration and Nationality Act (INA) provides that individual aliens outside the United States are "inadmissible"—or generally barred from admission to the country —on health, criminal, security, and other grounds set forth in the INA. However, the INA also grants the Executive several broad authorities that could be used to exclude certain individual aliens or classes of aliens for reasons that are not specifically set forth in the INA. Section 212(f) of the INA

The provisions currently in Section 212(f)—which have been part of the INA since its enactment in 1952 —state, in relevant part, that 
Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate. Legislative history materials from the time of the INA's enactment suggest that these provisions were seen to grant the President broad authority to bar or impose conditions upon the entry of aliens, and Presidents over the years have relied upon Section 212(f) to suspend or restrict the entry of various groups of aliens, often (although not always) in conjunction with the imposition of financial sanctions upon them. Among those so excluded have been aliens whose actions "threaten the peace, security, or stability of Libya"; officials of the North Korean government or the Workers' Party of North Korea; aliens who have participated in "serious human rights violations"; and others noted in Table 1 below. Neither the text of Section 212(f) nor the case law to date suggests any firm legal constraints upon the President's exercise of his authority under Section 212(f), as is explained below. However, future executive actions under INA § 212(f) could potentially be seen to raise legal issues that have not been prompted by the Executive's prior exercise of this authority. The central statutory constraint imposed on Section 212(f)'s exclusionary power is that the President must have found that the entry of any aliens or class of aliens would be "detrimental to the interests of the United States" in order to exclude the alien or class of aliens. The statute does not address (1) what factors should be considered in determining whether aliens' entry is "detrimental" to U.S. interests; (2) when and how proclamations suspending or restricting entry should be issued; (3) what factors are to be considered in determining whether particular restrictions are "appropriate"; or (4) how long any restrictions should last. Judicial Constructions of Section 212(f)

The limited case law addressing exercises of presidential authority under Section 212(f) also supports the view that this provision of the INA confers broad authority to suspend or restrict the entry of aliens. Key among these cases is the Supreme Court's 1993 decision in Sale v. Haitian Centers Council, Inc. , which held that the U.S. practice of interdicting persons fleeing Haiti outside U.S. territorial waters and returning them to their home country without allowing them to raise claims for asylum and withholding of removal did not violate either the INA or the United Nations Convention Relating to the Status of Refugees. The U.S. practice had been established by Executive Order 12807, which was issued, in part, under the authority of Section 212(f) of the INA and "suspend[ed] the entry of aliens coming by sea to the United States without necessary documentation." Most notably, Section 214(a)(1) prescribes that the "admission of any alien to the United States as a nonimmigrant shall be for such time and under such conditions as [the Executive] may by regulations prescribe." Section 215(a)(1) similarly provides that "it shall be unlawful for any alien" to enter or depart the United States "except under such reasonable rules, regulations, and orders, and subject to such limitations and exceptions as the President may prescribe." For example, President Carter cited to Section 215(a) when authorizing the revocation of immigrant and nonimmigrant visas issued to Iranians during the Iran Hostage Crisis.
The Immigration and Nationality Act (INA) provides that individual aliens outside the United States are "inadmissible"—or barred from admission to the country—on health, criminal, security, and other grounds set forth in the INA. However, the INA also grants the Executive several broader authorities that could be used to exclude certain individual aliens or classes of aliens for reasons that are not specifically prescribed in the INA.
Section 212(f) of the INA is arguably the broadest and best known of these authorities. It provides, in relevant part, that
Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate.
Over the years, Presidents have relied upon Section 212(f) to suspend or otherwise restrict the entry of individual aliens and classes of aliens, often (although not always) in conjunction with the imposition of financial sanctions upon these aliens. Among those so excluded have been aliens whose actions "threaten the peace, security, or stability of Libya"; officials of the North Korean government; and aliens responsible for "serious human rights violations."
Neither the text of Section 212(f) nor the case law to date suggests any firm legal limits upon the President's exercise of his authority to exclude aliens under this provision. The central statutory constraint imposed on Section 212(f)'s exclusionary power is that the President must have found that the entry of any alien or class of aliens would be "detrimental to the interests of the United States." The statute does not address (1) what factors should be considered in determining whether aliens' entry is "detrimental" to U.S. interests; (2) when and how proclamations suspending or restricting entry should be issued; (3) what factors are to be considered in determining whether particular restrictions are "appropriate"; or (4) how long any restrictions should last. The limited case law addressing exercises of presidential authority under Section 212(f) also supports the view that this provision confers broad authority to bar or impose conditions upon the entry of aliens. Key among these cases is the Supreme Court's 1993 decision in Sale v. Haitian Centers Council, Inc., which held that the U.S. practice of interdicting persons fleeing Haiti outside U.S. territorial waters and returning them to their home country without allowing them to raise claims for asylum or withholding of removal did not violate the INA or the United Nations Convention Relating to the Status of Refugees. The U.S. practice had been established by Executive Order 12807, which was issued, in part, under the authority of Section 212(f) and "suspend[ed] the entry of aliens coming by sea to the United States without necessary documentation." However, depending on their scope, future executive actions under Section 212(f) could potentially be seen to raise legal issues that have not been prompted by the Executive's prior exercises of this authority.
Beyond Section 212(f), other provisions of the INA can also be seen to authorize the Executive to restrict aliens' entry to the United States. Most notably, Section 214(a)(1) prescribes that the "admission of any alien to the United States as a nonimmigrant shall be for such time and under such conditions as [the Executive] may by regulations prescribe." Section 215(a)(1) similarly provides that "it shall be unlawful for any alien" to enter or depart the United States "except under such reasonable rules, regulations, and orders, and subject to such limitations and exceptions as the President may prescribe." For example, President Carter cited Section 215(a)—rather than Section 212(f)—when authorizing the revocation of immigrant and nonimmigrant visas issued to Iranian citizens during the Iran Hostage Crisis.