As tools, extradition and mutual legal assistance can take many different forms. The possibilities depend not only on the existence, age, and contents of a valid international agreement, but also on the type of offense and on the legislation and practice in a country. Extradition is the process by which a person charged with an offense is forcibly transferred to a state for trial, or a person convicted of an offense is forcibly returned for the enforcement of punishment. Among the common conditions included in extradition agreements are the double criminality requirement, a refusal to extradite nationals, and the political offense exception. The process of extradition may be lengthy. The purpose of mutual legal assistance is to get a foreign state to assist in other ways in the judicial process, for example by securing the testimony of possible victims, witnesses, or expert witnesses. Generally, mutual legal assistance is based on bilateral or multilateral treaties. The scope of measures that can be requested under mutual legal assistance is rather large, and the practice appears to be moving towards a constant expansion of this scope. Grounds for refusal for granting a request for mutual legal assistance include the absence of double criminality; the offense is regarded as a fiscal offense; and the granting of mutual legal assistance would be counter to the vital interests of the requested state. Some changes in mutual legal assistance procedures have been that conditions and grounds of refusal have been tightened or entirely eliminated; and the process has been expedited. Some of the changes in the extradition regime have been a broader scope of offenses; fewer grounds for refusal; and a trend toward mutual recognition and the “backing of warrants.” The Palermo Conventions, negotiated between 1998 and 2000, reflects in many ways the changes of extradition and mutual legal assistance. It includes many provisions that are new for practitioners in many countries, and may well improve the day-to-day practice of international cooperation. 38 footnotes