The Pope has granted broad powers to the archbishop he picked to overhaul the Legionaries of Christ following revelations that the order's founder led a double life.
A decree approved by Benedict XVI and published on the Legionaries' website says Archbishop Velasio De Paolis can override the Legionaries' own constitutions as he goes about reforming the order and purging it of its institutional abuses.
The conservative order once hailed by the Vatican for its orthodoxy and ability to recruit priests fell into disarray starting last year as it admitted that its founder, the Rev Marciel Maciel, sexually abused seminarians and fathered at least three children.
In a May 1 statement, the Vatican said Maciel had built a system of power built on obedience and deceit that allowed his criminal and immoral misdeeds to go unchecked for decades.
It said the Legionaries needed to be profoundly purified to survive, with the order's essential spirit redefined, its founding constitutions revised and the systemic abuse of authority corrected.
In the decree dated July 9, the Vatican said Archbishop De Paolis would have broad powers of governance to carry out those tasks.
The order's current leadership - accused by critics of having covered up for Maciel's misdeeds - remains in place "unless it becomes necessary to provide otherwise", the decree says.
Questions about the fate of the current leadership and control of the group's finances have swirled since the Vatican announced it was taking over the order.
News reports have estimated the Legion has assets totalling £22 billion in a holding company headed by the order's current number two.
Appeals against Archbishop De Paolis' actions go to the Pope himself, the decree states.
Maciel founded the Legion in his native Mexico in 1941. The Legionaries now claim a membership of more than 800 priests and 2,500 seminarians in 22 countries, along with 70,000 members in its lay movement, Regnum Christi.
The order runs schools, charities, Catholic news outlets, seminaries for young boys, and universities in Mexico, Italy, Spain and elsewhere.