The rape and murder of 7-year-old Megan Kanka in July 1994 was pivotal to the development of Federal and State laws regarding the collection and dissemination of information about sex offenders. All States and the Federal Government now have their own versions of what is called Megan's Law. Some researchers claim that the registration laws are ineffective at best and that notification laws may have an effect opposite from what was intended. No data exist to indicate that such laws actually reduce recidivism. Nearly every provision in these statutes has been challenged by offenders subject to them. Challenges have been based on ex post factor, bill of attainder, double jeopardy, and cruel and unusual punishment. Other challenges have looked at the nature of the individual interest involved, the intrusiveness of the government's action, the knowledge of the offender, or the jurisdiction over the offender. Most challenges to registration laws have not been upheld. Challenges to notification provisions have met with greater success, because notification is perceived as a more onerous burden on individual rights. Further legislation and legal challenges are likely. 244 reference notes