Michel-Louis Guérard des Lauriers

Michel-Louis Guérard des Lauriers was a French Catholic clergyman and theologian who was a member of the Dominican Order but was eventually excommunicated from the Catholic Church. He was involved in contemporary traditionalist Catholicism, both in France and the wider world, especially in support of the Tridentine Mass. An early adopter of sedevacantism, a theory claiming that Pope Paul VI was not a legitimate Pope, he changed his position by 1979, creating a new theory known as sedeprivationism. Also called the ‘Cassiacum Thesis’, it is sometimes considered adjacent to or a sub-set of sedevacantism.