Jacob Wetterling
Wetterling's ride home was interrupted by an armed man wearing a nylon mask who ordered the boy's companions to flee. Wetterling has not been seen since. Investigators later learned that, unknown to local law enforcement, halfway houses in St. Joseph housed sex offenders after their release from prison. Wetterling's disappearance transformed his mother, Patty, a self-described "stay-at-home mom," into a tireless advocate for missing children. The Wetterling Act required states to establish stringent registration programs for sex offenders – including life-long registration for a subclass of offenders classified as sexual predators. Megan's Law in Pennsylvania has been enacted, repealed, re-enacted and subsequently amended almost yearly since 1995.   
Pam Lychner
Awaiting Lychner at a vacant house was a twice-convicted felon who brutally assaulted the former flight attendant. Her life was saved when her husband arrived on the scene and interrupted the attack. Lychner helped to craft the language of a bill that established a national computer database to track sex offenders. The bill was named the "Pam Lychner Sexual Offender Tracking and Identification Act of 1996" to honor the activist after she and her two daughters were killed in an airplane accident  July 1996.

Megan Kanka
The neighbor who invited Megan Kanka to see his puppy was a twice-convicted offender, who raped and murdered her, then dumped her body in a nearby park. Megan's grieving parents said they never would have let their daughter travel their neighborhood freely if they had been alerted to the presence of a convicted sex offender living across the street from their residence. Congress passed the Federal version of "Megan's Law," another amendment to the Violent Crime Control and Law Enforcement Act of 1994, in 1996. In brief, the statutes require states to establish registration programs so local law enforcement will know the whereabouts of sex offenders released into their jurisdictions, and notification programs so the public can be warned about sex offenders living in the community

 

Enactment (or Megan's Law I)
On October 21, 1995, Governor Ridge signed into law Act 24 of 1995, which became effective on April 21, 1996. Act 46 of 1996 amended Act 24 of 1995 and became effective on May 22, 1996. 

Repealed
In a decision filed October 6, 1998 in Apealee v. Edward James Hayle, the Superior Court of Pennsylvania found portions of "Megan's Law" to be unconstitutional. 
On June 30, 1999, the Pennsylvania Supreme Court, in Commonwealth v. Williams, struck down all relevant provisions of the Act relating to sexually violent predators, with one dissenting opinion. In a second ruling also released on June 30, the Pennsylvania Supreme Court, in Commonwealth v. Gaffney, unanimously upheld the Pennsylvania Superior Court's ruling that the registration portion of the Act was constitutional. 

Re-enactment (or Megan's Law II)
The Pennsylvania Legislature unanimously re-enacted Megan's Law and on May 10, 2000, the Governor signed into law Act 18 of 2000.  This law became effective on July 8, 2000.  

Amendments
Act 113 of 2000 amended Act 18 of 2000 by adding a new offense, sexual exploitation of children. Pursuant to statute, this amendment became effective February 18, 2001.  
On November 24, 2004, Governor Edward Rendell signed into law Act 152 of 2004, which made significant changes to Megan's Law. Most notably, information on all registered sex offenders is now available to the public through the Internet. Additionally, two new crimes were added to the list of offenses for which registration, and Internet notification, is required under Megan’s Law: Luring a Child into a Motor Vehicle (18 Pa. C.S. § 2910) and Institutional Sexual Assault (18 Pa. C.S. § 3124.2). 
Act 98 of 2008, which became effective on December 8, 2008, also resulted in the following amendments to Megan’s Law.  
10 Year Registration Offenses:
• Luring a Child into a Motor Vehicle or Structure (18 Pa. C.S. § 2910)
• Offenders convicted of an attempt, conspiracy or solicitation to commit any of the offenses under 10-year registration or lifetime registration
• Offenders convicted in jurisdictions outside the Commonwealth of an equivalent offense listed under the 10-year registration where the conviction occurred under a former law of the Commonwealth, in another state, territory, Federal court, the District of Columbia, or where the offender was sentenced by court martial, or where the offender was required to register under a sexual offender statute in the jurisdiction where the offender was convicted, and the offender:
   o Resides in the Commonwealth; or
   o Is employed or carries on a vocation in the Commonwealth; or
   o Is a student in the Commonwealth.

Lifetime Registration Offenses:
• Offenders convicted in jurisdictions outside the Commonwealth of an equivalent offense listed under the 10-year registration where the conviction occurred under a former law of the Commonwealth, in another state, territory, Federal court, the District of Columbia, or where the offender was sentenced by court martial, or where the offender was required to register under a sexual offender statute in the jurisdiction where the offender was convicted, and the offender:
   o Resides in the Commonwealth; or
   o Is employed or carries on a vocation in the Commonwealth; or
   o Is a student in the Commonwealth.

Juvenile Sex Offender Involuntary Civil Commitment
On August 14, 2003, Governor Edward Rendell signed into law Act 21 of 2003, which added a new mandate for the Sexual Offenders Assessment Board. Act 21, which became effective on February 10, 2004, requires the SOAB to assess certain juvenile sex offenders aging out of the juvenile justice system for involuntary commitment., where certain adolescent sex offenders aging out of the juvenile justice system were to be considered for involuntary civil commitment.  Act 21 became effective on February 10, 2004.

 

The Adam Walsh Child Protection and Safety Act is a federal statute that was signed into law by U.S. President George W. Bush on July 27, 2006. The Walsh Act organizes sex offenders into three tiers and mandates that Tier 3 offenders (the most serious tier) update their whereabouts every three months with lifetime registration requirements. Tier 2 offenders must update their whereabouts every six months with 25 years of registration, and Tier 1 offenders must update their whereabouts every year with 15 years of registration. Failure to register and update information is a felony under the law. The Act is also known as the Sex Offender Registration and Notification Act (SORNA) This piece of legislation was thought to cost goverments millions.  So think that it does nothing to protect children and reduce recidivism for sexual offenders.  LEGISLATION THAT EFFECTIVELY MADE PA A STATE THAT HAS ADOPTED THE MAJORITY OF PROVISIONS TO BE IN COMPLIANCE WITH SORNA. This was originally SB 1183 signed into law December 20, 2011 is now known as ACT 111 and ACT 91