In what circumstances will a defendant be able to deny a crime committed during his illegal detention?

We do not mean to suggest that unlawful government conduct may not serve as a basis for immunizing a person from criminal liability. Entrapment and "outrageous government conduct" are examples of instances in which we, and other courts, have held that persons may not be convicted of particular offenses. When it is claimed that the police have exploited an illegal arrest by creating a situation in which a given criminal response is predictable, we believe that a better approach would be to determine whether the government's prosecution of the crime would abridge fundamental protections against unfair treatment. See, e.g., United States v. Stenberg, 803 F.2d 422, 428-32 (9th Cir.1986) (discussing both "outrageous government conduct" and entrapment as defenses to criminal prosecutions). Affording a substantive defense to a crime committed during an illegal detention when particular circumstances so warrant provides a more rational and measured way of protecting individual rights than does the application of fourth amendment analysis to all such cases. Equally important, extending the exclusionary rule to bar prosecution of new crimes is simply unwarranted both from a historical and a practical standpoint.