NORTH CAROLINA, USA (AP) — Convicted sex offenders are pushing back against North Carolina laws they contend deprive them of constitutional rights without protecting children.

Two anonymous sex offenders and a Raleigh-based, national, non-profit organisation that advocates for them filed a federal lawsuit on Monday challenging the state laws. It’s part of an effort to trim sex registry laws that now require more than 800,000 convicts nationwide to register their names, addresses and photographs, perhaps for as long as they live.

State Attorney General Josh Stein will defend the law and “believes that protecting people from sex offenders is critically important to public safety”, spokeswoman Laura Brewer said in an email.

The offenders contend that North Carolina’s law violates the US Constitution by imposing added penalties after conviction and sentencing, for example by extending the years an offender must register. The lawsuit says they are unconstitutionally banned from practising their religion by being forbidden from entering churches, and from petitioning their government representatives by effectively being excluded from the General Assembly building.

The law also violates constitutional due process rights by depicting all offenders as dangerous to young children, and doesn’t provide any way for offenders to challenge such a claim, the lawsuit said.

“In fact, the individual plaintiffs in this case have already been found not to be a danger to children, yet they are subjected to a serious deprivation of liberty, despite that determination,” the lawsuit said.

Though most people would believe the registries are designed to protect the public against child molesters, states have expanded the registries to include sexually active teenagers and people arrested for public urination, said JJ Prescott, a University of Michigan law professor who studies post-release sex offender laws.

Judges, meanwhile, have increasingly noted studies finding no public safety benefit to many aspects of these registries, even as they cause collateral damage to the friends and families of offenders, he said.

“I think there has been a shift in the mood on these cases,” Prescott said.

The two offenders asked the court to remain unidentified, citing fears that they and their families risk harassment and abuse.

“John Doe 1” was convicted in 2009 of two counts of misdemeanour sexual battery against a 30-year-old woman, and is not on probation or subject to any court-ordered restrictions, the lawsuit said. “John Doe 2” was convicted in 2011 of misdemeanour sexual battery after sex with a 16-year-old girl he had coached, the lawsuit said.

Similar lawsuits have been filed in the past two years in Illinois, Wisconsin, Louisiana, Alabama, Colorado, Nevada and Idaho.

In August, the 6th US Circuit Court of Appeals ruled that significant changes to Michigan’s sex offender registry law cannot be applied retroactively, because doing so would unconstitutionally stiffen punishments after the offenders’ convictions.

In December, the 4th US Circuit Court of Appeals in Richmond, Virginia, overruled North Carolina’s prohibitions against offenders going to places where minors gather for educational, recreational or social programmes, or being within 300 feet of locations where children are supervised.

The US Supreme Court next month takes up a free speech challenge to a North Carolina law banning sex offenders from using

Facebook and other social networking sites minors can join.