Afew years ago, I covered a particularly odious court case in which a New Zealand man was convicted of organising underage sex tours to Thailand.
The detail was just as awful as you might expect, but I was struck at the time by how difficult it is for police in Southeast Asia to keep up with the thousands of tourists who visit their countries with the intent of abusing children.
It's a hideous thought.
In New Zealand and in other developed countries, it's our expectation police and government authorities will continue to monitor convicted sex offenders once they're released into the wider community.
For the most part, although there are occasional devastating exceptions, our monitoring and support systems for convicted child sex offenders are generally pretty good.
But our responsibility to protect children from sex offenders extends beyond our borders.
Australia has become the first in the world to ban convicted child sex offenders from travelling overseas, even once they've completed their prison sentence.
About 20,000 people on the child sex offender register will have their Australian passports cancelled, and can only apply to travel in extraordinary circumstances.
The period of paedophiles' respective travel bans is relative to their crimes.
In Australia, 3200 people considered the most dangerous offenders will never be allowed to travel overseas again.
We should do the same.
And don't get me wrong. When it comes to justice, I'm not a lock-them-up-and-throw-away-the-key kind of guy.
I think prison, though still necessary, is a medieval concept.
I agree with the Bill English who once called prisons a moral and fiscal failure (rather than the Bill English who is building a new one).
But any one person's civil liberties and freedom needs to be weighed up against the collective interests of society, a test that should apply to all of us whether convicted of crimes or not.
These days you can get a ticket to Thailand or Cambodia for a few hundred bucks. A direct flight to the front line of international child trafficking and under-age prostitution. We should do everything we can to stop it.
• Jack Tame is on NewstalkZB Saturdays, 9-noon.