https://www.usmarshals.gov/megans-law-faqs.html
International Megan’s Law – FAQ Sheet

What is the International Megan’s Law and when was it passed?
On February 8, 2016, President Barack Obama signed the International Megan’s Law to Prevent Child Exploitation and Other Sexual Crimes through Advanced Notification of Traveling Sex Offenders, more commonly referred to as “International Megan’s Law” (IML).

Whom does the International Megan’s Law apply to?
The IML has notable provisions that may impact all registered sex offenders who intend to travel outside of the United States.

Whom do I notify that I am traveling and when do I need to do so?
The IML and the relevant Sex Offender Registration and Notification Act (SORNA) guidelines require that all registered sex offenders report international travel to their respective sex offender registry at least 21 days prior to departure from the United States. Emergency travel must be reported as soon as travel is scheduled.

Can I be arrested if I don’t report travel?
Although not all states require that you report international travel, you may be subject to federal prosecution if you fail to provide notice of international travel or file a false travel notice with your registry.

Can I personally submit an International Travel Form to the United States Marshals Service (USMS), National Sex Offender Targeting Center?
No. All International Travel Notices must be completed and submitted by your local sex offender registry.

Does the USMS decide if a sex offender can enter a foreign country?
No. The USMS does not make any recommendations, nor does it have the authority to deny or approve entry of an offender into a foreign country. It is up to sovereign governments to decide to whom they will allow entry, and to whom entry will be denied. Notification of travel does not authorize entry into a foreign country, nor does it serve as permission to travel. It is highly recommended that any offender traveling internationally contact the consulate or embassy of their anticipated destination to determine if entry will be authorized.

Is the USMS the only law enforcement agency who sends international travel notices?
No. International travel notices may be sent by other law enforcement agencies without knowledge of, or consultation with, the USMS.

Can I make a complaint if I am a victim of an erroneous notification?
Any individual who traveled internationally and was denied entry into a country based upon a notification believed to have been made in error by the USMS may make a complaint. The complaint form can be located here. Note that this form is only for the individual who was the subject of a USMS notice, and not family members or other traveling companions.

Whom may I contact if I have more questions?
You may contact the USMS National Sex Offender Targeting Center at 202-616-1600.

No complaints can be processed without the submission of a Department of Justice Certification of Identity which can be found here.