Megan's Law, a New Jersey sex offender criminal registration law, has been successfully challenged in Federal district court. In 1995, the Federal district court judge issued a brief order granting a preliminary injunction that prohibited implementation of the Tier Two aspect of Megan's Law. The defendant, a convicted sex offender released from prison, challenged the application of Tier Two status to him, an administrative determination that he was at moderate risk of reoffending. Megan's Law raises several possible challenges: (1) it is an ex post facto law in that it inflicts additional punishment long after commission of the offense; (2) due process is violated because there is a protected liberty interest at stake, the offender's reputation and privacy; (3) the law is a form of double jeopardy; and (4) the law creates a stigma that may be characterized as cruel and unusual punishment. Recent case law tends to uphold laws requiring the registration of sex offenders but either draws the line or issues a caution as the basis for disclosure expands beyond law enforcement and prosecutorial agencies. 15 footnotes