The Vatican obtained the intervention of President George W. Bush, who agreed the pope should have immunity against such prosecutions because he was an acting head of a foreign state.

Protests are growing against Pope Benedict XVI’s planned trip to Britain, where some lawyers question whether the Vatican’s implicit statehood status should shield the pope from prosecution over sex crimes by pedophile priests.

More than 10,000 people have signed a petition on Downing Street’s web site against the pope’s 4-day visit to England and Scotland in September, which will cost U.K. taxpayers an estimated 15 million pounds ($22.5 million). The campaign has gained momentum as more Catholic sex abuse scandals have swept across 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 in other countries.

Lawyers are divided over the immunity issue. Some argue that the Vatican isn’t a true state, while others note the Vatican has national relations with about 170 countries, including Britain. The Vatican is also the only non-member to have permanent observer status at the U.N.

Then again, no other top religious leaders enjoy the same U.N. privileges or immunity, so why should the pope?