Lawyers for over 200 sex offenders have claimed that the practice – introduced last year in Butts County in the US state of Georgia – violates their privacy.

The signs which appeared in their front gardens yesterday read “Warning! No Trick-or-Treat at this Address!!” and will not be removed until Sunday 3 November.

Attorney Mark Yurachek told Fox 5 Atlanta: “The law allows the sheriff to put a list of registered sex offenders at his office, at the courthouse, on the internet. It does not allow him to go door-to-door telling people you have a sex offender living next door to you.

“I’m just not sure that this kind of action makes your kids any safer. It just makes your constitutional rights less safe.”