Extradition is defined as the "official surrender of a fugitive from justice, regardless of his consent, by the authorities of the state of residence to the authorities of another state for the purpose of criminal prosecution or the execution of a sentence." Every extradition case may be regarded as an individual agreement under international law, notwithstanding that the parties may also have established general extradition relations by concluding a bilateral treaty or acceding to a multilateral extradition treaty. A discussion of the availability of extradition mechanisms focuses on alternatives to international extradition agreements, the negotiation of multilateral and bilateral instruments, and succession to existing instruments. A section on the problems in the preparation of extradition requests addresses dual criminality and the "list" approach, as well as political, tax, and fiscal offenses. A discussion of the problems in the execution of extradition requests considers refusal based on nationality and alternatives, refusals based on the principle of ne bis in idem, in absentia convictions and other humanitarian concerns, representation of the requesting state, and provisional arrest and sufficiency of documentation. The concluding section examines policy issues concerning impediments to extradition. The issues reviewed are policy development and bridging the gaps between legal systems, causes of delay and misunderstanding, and technical-cooperation activities and follow-up.