LONDON–Protests are growing against Pope Benedict XVI's planned trip this fall to Britain, where the legal world is debating whether the Vatican's implicit statehood could shield the Pope from potential prosecution related to sex crimes by pedophile priests.

More than 10,000 people have signed an online petition to Prime Minister Gordon Brown opposing the Pope's four-day visit to England and Scotland in September.

The campaign has gained momentum as more Catholic sex- abuse scandals shake Europe.

Although Benedict has not been accused of any crime, senior British lawyers are now examining whether the Pope should have immunity as a head of state and whether he could be prosecuted under the principle of universal jurisdiction for an alleged systematic cover-up of sexual abuses by priests.

Universal jurisdiction – a concept in international law – allows judges to issue warrants for nearly any visitor accused of grievous crimes, no matter where they live. British judges have been more open to the concept than those elsewhere.

Lawyers are divided over the immunity issue. Some argue the Vatican isn't a true state, while others note it has national relations with about 170 countries, including Britain.

David Crane, former chief prosecutor at the Sierra Leone war crimes tribunal, said it would be difficult to implicate the Pope in anything criminal.

"It's a fascinating kind of academic, theoretical discussion," said Crane, who prosecuted Liberia's Charles Taylor when he was still a sitting head of state. "At this point, there's no liability at all."

But Geoffrey Robertson, who as a UN appeals judge delivered key decisions on the illegality of conscripting child soldiers and the invalidity of amnesties for war crimes, believes it could be time to challenge the immunity of the Pope – and Britain could be the place.

"Unlike in the United States, where the judges commonly uphold what the executive says, the British courts don't accept these things at face value," Robertson said on Saturday.

Lawyers question whether an alleged systematic cover-up could be considered a crime against humanity – a charge usually reserved for the International Criminal Court – and whether it could be pursued under universal jurisdiction.

"My guess is the weight of opinion would allow the Pope to enjoy immunity," said Hurst Hannum, of Tufts University. "It's not automatically clear that the Holy See is a state, although it's treated as one for almost every purpose."

Spain and Britain jointly pioneered the universal jurisdiction concept when, in 1998, Britain executed a Spanish arrest warrant for former Chilean dictator Augusto Pinochet on torture claims. He was under house arrest in London until ruled unfit to stand trial in 2000.