Both the U.S. House and Senate have signed off on a bill to brand registered sex offenders as such on their passports and require federal officials to notify foreign governments whenever certain offenders intend to travel there. The bill is now on its way to President Obama; it's unclear whether he'll sign.

If he does, it will be "the first time in U.S. history that any such special designation will appear on the passports of any U.S. citizens," writes lawyer and New America Foundation Senior Fellow David Post at The Volokh Conspiracy, "and I think it should send at least a small chill down all of our spines."

Dubbed "International Megan's Law," the measure—sponsored by Rep. Chris Smith (R-N.J.)—says the secretary of state must impart a "visual designation" in "a conspicuous location" on the passports of all "covered sex offenders." Covered sex offenders include anyone whose victim was a minor.

This is where people start to lose sympathy—for better or worse, most can't muster much concern for the constitutional rights of rapists and child molesters. But because of our overbroad sex-offender registry requirements, "covered sex offenders" may include teens who text each other explicit photos, men who offer to pay for sex with someone who is—known or unbeknownst to them—under 18, and statutory rape cases where the the age disparity between offender and victim is small and the relationship consensual. These people are already required to register with state and federal officials as sex offenders, thereby subjecting them to rules about where they can live, work, etc. Now they may face a lifetime of trouble traveling and perhaps even be prevented from entering certain countries entirely.

Beyond the injustice of it, there's no evidence that the law—applied broadly or even only to those accused of the most serious sex crimes—would actually thwart international human trafficking or sex tourism, the stated goal of the bill according to Rep. Smith. For one thing, the passport requirement would only apply to sex offenders done serving their sentences, obviously. But we have little reason to think most of these people will reoffend. As Reason contributor Lenore Skenazy points out at the New York Post, "the general belief is that sex offenders have one of the highest recidivism rates around—that they get out of prison only to offend again. Surprisingly, the opposite is true." A Bureau of Justice report places the sex-offender recidivism rate at 5.3 percent, a recidivism rate lower than any crime other than murder.

What's more, when it comes to those who have committed the most heinous crimes or are the most likely to reoffend, we already have a mechanisms in place to either prevent them from getting passports or notify foreign governments when they're traveling abroad. The Secretary of State can deny passports to people convicted of certain sex crimes, and Immigration and Customs Enforcement's (ICE) "Operation Angel Watch" already notifies foreign officials when Americans convicted of certain sex crimes are traveling there.

And the reason ICE knows the travel habits of these sex offenders? Because all people on state sex offender registries—regardless of why they're there or how long ago their crimes were committed—are required under federal law to "inform his or her residence jurisdiction of any intended travel outside of the United States at least 21 days prior to that travel."

The new law would build on this, also establishing the feds must notify foreign officials whenever covered sex offenders intend to travel there, adding the special seal to covered sex offender passports, and setting up an "Angel Watch Center" within the Department of Homeland Security. The Angel Watch Center would receive information from foreign governments about sex offenders traveling to America and share this information with the Justice Department and state and local law-enforcement agencies, thereby instituting a globally coordinated system to monitor the movements of ostensibly free people. Congress has authorized $6 million per year for 2017 and 2018 to carry out the act's provisions.