<P> In the case of Soering v. United Kingdom, the European Court of Human Rights ruled that the United Kingdom was not permitted under its treaty obligations to extradite an individual to the United States, because the United States' federal government was constitutionally unable to offer binding assurances that the death penalty would not be sought in Virginia courts . Ultimately, the Commonwealth of Virginia itself had to offer assurances to the federal government, which passed those assurances on to the United Kingdom, which extradited the individual to the United States . </P> <P> Additional problems can arise due to differing criteria for crimes . For instance, in the United States, crossing state lines is a prerequisite for certain federal crimes (otherwise crimes such as murder are handled by state governments except in certain circumstances such as the killing of a federal official). This transportation clause is absent from the laws of many countries . Extradition treaties or subsequent diplomatic correspondence often include language providing that such criteria should not be taken into account when checking if the crime is one in the country from which extradition should apply . </P> <P> To clarify the above point, if a person in the United States crosses the borders of the United States to go to another country, then that person has crossed a federal border, and federal law would apply in addition to state law . Crossing state lines (within the U.S.) in committing a crime could also create federal jurisdiction . In addition, travel by airplane in the United States subjects one to federal law, as all airports are subject to federal jurisdiction . </P> <P> It is unlawful for U.S. citizens to enter or exit the United States without a valid U.S. passport or Western Hemisphere Travel Initiative--compliant passport - replacement document, or without an exception or waiver . An application is required for the issuance of a passport . If a fugitive being extradited to the United States refuses to sign a passport application, the consular officer can sign it "without recourse". </P>

Countries with no extradition agreement with the us