Amends the Federal criminal code to establish criteria for the imposition of the death penalty for treason and espionage. Requires the Government, for an offense punishable by death, to serve notice upon the defendant a reasonable time before trial or acceptance of a plea that it intends to seek the death penalty, as well as notice of the aggravating factors upon which it will rely. Requires a separate sentencing hearing before a jury or the court upon motion by the defendant when the defendant is found guilty or pleads guilty to an offense punishable by death. Provides that no presentence report shall be prepared in such cases. Allows the defendant and the Government to present any information relevant to sentencing, without regard to the rules of evidence, but permits information to be excluded where its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading of the jury. Specifies mitigating factors which the defendant must establish by a preponderance of the information and aggravating factors which the Government must prove beyond a reasonable doubt. Sets forth special aggravating factors with respect to the crimes of treason and espionage. Includes among the mitigating factors that the defendant was less than 18 years old at the time of the crime. Conditions imposition of the death penalty on a unanimous finding by the jury that: (1) some aggravating factor exists in addition to a threshold factor; and (2) the aggravating factor sufficiently outweighs any mitigating factor found to exist. Directs the court to impose the death penalty upon a finding that such sentence is justified. Requires the court to impose a mandatory life sentence if one or more aggravating factors are found and the death penalty is not imposed. Limits the circumstances under which the offense of delivering defense information to aid foreign governments is punishable by death. Establishes procedures for appeal from a death sentence. Requires the court of appeals, upon considering the record and the information and procedures of the sentencing hearing, and any special finding, to affirm the decision if: (1) the sentence was not imposed under influence of passion, prejudice, or arbitrariness; and (2) the information supports the finding of aggravating factors or the absence of mitigating factors. Requires the court to provide a written explanation of its determination.