The move, which came into effect on Thursday, ends 80 years of automatic adoption brought in by the Lateran treaties between the Pope and the Italian parliamentary system.
The Papal office said there were too many laws in the Italian civil and criminal codes and that many of them conflicted with the Church’s principles.
Vatican City State, the smallest sovereign state in the world, will now consider laws passed by parliament on an individual basis before adopting them as their own.
The decision also applies to international treaties and follows its recent refusal to approve a UN declaration advocating the decriminalisation of homosexuality.
The Roman Catholic Church has in the past spoken out against efforts to legalise same sex civil unions and euthanasia, and the divorce from Italian law could be seen as a bid to protect the Church’s position on these and other ethical issues.