<P> The Sixth Amendment calls for trial "by an impartial jury of the State and district wherein the crime shall have been committed ." Within the federal court system, Rule 18 of the Federal Rules of Criminal Procedure specifies which federal court may hear a particular criminal case: </P> <Dl> <Dd> Unless a statute or these rules permit otherwise, the government must prosecute an offense in a district where the offense was committed . The court must set the place of trial within the district with due regard for the convenience of the defendant and the witnesses, and the prompt administration of justice . </Dd> </Dl> <Dd> Unless a statute or these rules permit otherwise, the government must prosecute an offense in a district where the offense was committed . The court must set the place of trial within the district with due regard for the convenience of the defendant and the witnesses, and the prompt administration of justice . </Dd> <P> Anderson, 328 U.S., at 703 holds: "(T) he locus delicti must be determined from the nature of the crime alleged and the location of the act or acts constituting it ." In Hyde v. United States, 225 U.S. 347 (1912) although none of the defendants had entered the District of Columbia as part of their conspiracy to defraud the United States, they were convicted because one co-conspirator had committed overt acts in Columbia (225 U.S., at 363). So conspiracy is a continuing offense committed in all the districts where a co-conspirator acts on the agreement . Similarly, In re Palliser, 136 U.S. 257 (1890) the sending of letters from New York to postmasters in Connecticut in an attempt to gain postage on credit, made Connecticut, where the mail he addressed and dispatched was received, an appropriate venue (136 U.S., at 266--268). See 18 U.S.C. § 3237 (a): </P>

Who defines some crimes as federal in jurisdiction