THE Vatican should be treated as a kind of ''rogue state'' by the rest of the world until it stops using statehood - and the ancient rules of the canon law - to protect paedophile priests.

So says Geoffrey Robertson, QC, the veteran human rights lawyer and United Nations judge, arguing that the Catholic Church is the only religion permitted under international law to claim the privileges of statehood and its leaders immunity from civil or criminal action.

Canon law ''defective'' ... Geoffrey Robertson and the Pope.

In his new book, The Case of the Pope: Vatican Accountability for Human Rights Abuse published as a Penguin special in Britain - and in Australia at the weekend - Mr Robertson urges the world to press the Catholic Church into abandoning canon law, the ancient set of ecclesiastical rules that also define disciplinary provisions for offences ranging from sex crimes to ordaining women.

However, these punishments, sometimes meted out under mediaeval written procedures run by fellow priests, allow ''neither cross-examination and medical examination, nor DNA testing'' and ''no punishment worthy of that name'', he says.