The law, named after Megan Kanka, a 7-year-old New Jersey girl who was raped and killed by a neighbor in 1994, requires convicted sex offenders to be registered with the government, making it easier to track their whereabouts. Their names can then be put into databases, allowing the public to do a quick online check to determine where offenders reside.

While the law now applies to all states, California Republican Rep. Dan Lungren is proposing a worldwide crackdown on high-risk sex offenders and sex trafficking.

Under his bill, convicted sex offenders would have to tell local law enforcement of their travel plans 21 days before leaving their country. That information would then be shared with diplomatic officials in foreign countries, who could keep track of the offenders. Lungren is already working with the Mexican government on the proposal.

"The idea is to notify law enforcement officials in those countries that people are traveling," said Lungren, who called sex trafficking "a plague on our region and our nation."