Extradition is the process by which a person wanted for (or convicted of) a crime in another country is seized by local law enforcement and delivered to the nation seeking to prosecute. The United States has extradition treaties with most of the other nations of the world. See 18 U.S.C. 3181. Each of these treaties is unique, however. So, before determining whether a person on American soil can or will be apprehended and extradited, the applicable treaty must be read and examined.
Generally speaking, if a foreign nation suspects that a person it wants to prosecute is currently on American soil, it will send a request for an arrest of that person to American federal law enforcement. If the U.S. government determines that its treaty with the other nation requires it to deliver to that nation a person currently on American soil, an American federal prosecutor will seek an arrest warrant and then an extradition certification for that person.
Once the person is in custody, the accused can attempt to prevent the transfer to the requesting nation. As a practical matter, it is normally difficult to succeed in preventing the transfer. The trial of the person’s guilt or innocence is not had on American soil – that happens in the requesting nation. In deciding whether to certify an extradition, an American court’s review is limited to determining: (1) whether the court has jurisdiction; (2) whether the offense charged is covered by the applicable treaty; (3) whether that treaty is in force; and (4) whether there is sufficient evidence to support a finding of probable cause for the charges. 31 U.S.C. § 3184.