A paramount principle of the law of extradition provides that a State may not surrender any individual for any offense not included in a treaty of extradition. This principle arises from the reality of extradition as a derogation of sovereignty. Extradition is an intrusion into the territorial integrity of the host State and a delimitation of the sovereign power of the State within its own territory. The act of extraditing amounts to a “delivery by the State of a person accused or convicted of a crime, to another State within whose territorial jurisdiction, actual or constructive, it was committed and which asks for his surrender with a view to execute justice.” As it is an act of “surrender” of an individual found in a sovereign State to another State which demands his surrender , an act of extradition, even with a treaty rendered executory upon ratification by appropriate authorities, does not imposed an obligation to extradite on the requested State until the latter has made its own determination of the validity of the requesting State’s demand, in accordance with the requested State’s own interests.
The principles of international law recognize no right of extradition apart from that arising from treaty. Pursuant to these principles, States enter into treaties of extradition principally for the purpose of bringing fugitives of justice within the ambit of their laws, under conventions recognizing the right of nations to mutually agree to surrender individuals within their jurisdiction and control, and for the purpose of enforcing their respective municipal laws. Since punishment of fugitive criminals is dependent mainly on the willingness of host State to apprehend them and revert them to the State where their offenses were committed, jurisdiction over such fugitives and subsequent enforcement of penal laws can be effectively accomplished only by agreement between States through treaties of extradition.
Deportation is the expulsion of a person or group of people from a place or country. All countries reserve the right to deport foreigners, even those who are longtime residents. In general, foreigners who have committed serious crimes, entered the country illegally, overstayed and/or broken the conditions of their visa, or otherwise lost their legal status to remain in the country may be administratively removed or deported. In many cases, deportation is done by the government’s executive apparatus, and as such is often subject to a simpler legal process (or none), with reduced or no right to trial, legal representation or appeal due to the subject’s lack of citizenship.
Deportation can also happen within a state, when (for example) an individual or a group of people is forcibly resettled to a different part of the country. If ethnic groups are affected by this, it may also be referred to as population transfer.
Extradition differs from deportation in that extradition is affected at the request of the state of origin whereas deportation is the unilateral act of the local state; extradition is based on offenses generally committed in the state of origin whereas deportation is based on causes arising in the local state; and extradition calls for the return of the fugitive to the state of origin whereas an undesirable alien may be deported to a state other than his own or the state of origin.
References: Oppenheim, International Law: A Treaties 362-369 (1912). Bishop, International Law 471 (1962). Terlindan v Arnes, 184 U.S. 270, 289 (1902). Factor v. Laubenheimer, 270 U.S. 276 (1933). Fenwick, Cases of International Law 448 (1951). Henckaerts, Mass Expulsion in Modern International Law and Practice, 1995. Cruz, Isagani. International Law, 2000.