ROME – As the U.S. bishops gear up for their own probe of four dioceses after Pope Francis turned down an apostolic visitation related to ex-Cardinal Theodore McCarrick, they face many questions, not least of which is whether there are precedents in Church law for such a review to be carried out by bishops rather than the pope.

At the moment, plans apparently call for investigations in the diocese of Metuchen and the archdioceses of Newark, Washington and New York – places where McCarrick served at various points as he rose up the Church’s ladder. Not yet clear is who’ll be running these investigations, under whose authority they’ll operate, and when they’ll begin.

Whatever happens, Father Fernando Puig, vice dean of the Canon Law faculty at Rome’s Opus Dei-run Pontifical University of the Holy Cross, said it won’t be the same as a papally-launched apostolic visitation.

From its origins, he said, “the apostolic visitation is something done in the name of the pope, in the name of the Holy See…There is no tradition that an episcopal conference can do a visitation.”

The Church, he said, has always handled crimes in one of two ways, the first being a “procedural” path which is similar to a civil process in which a person has a lawyer, perhaps goes to trial, and a sentence is reached. The other, Puig said, is the apostolic visitation, which is typically done in a “hidden” way to ensure discretion.

While there are different types, including a diocesan visitation, when someone “visits” a diocese to observe, research and report back to the Vatican, they are always done “only by the apostolic see in the name of the pope.”

The U.S. bishops invited Francis to open an apostolic visitation into the McCarrick scandals in August, but they were told in a Sept. 13 audience with the pope in Rome that he’s not inclined to take that path.

According to Puig, there are no general rules in canon law for how an apostolic visitation is structured, because “every apostolic visitation is an (individual) case,” and the person selected as visitor is usually given a document spelling out their task for the specific mission entrusted to them.

The pope can give his power to a visitor, usually a cardinal or a bishop, although in the case of a 2008-2014 apostolic investigation into women’s religious orders in the U.S., it was a sister.

“But, always they were someone in representation of the supreme pontiff, of the Holy See,” Puig said, adding that the Vatican could theoretically give the U.S. bishops power to do an investigation, but it would be done publicly and would still always be “in name of the Holy See.”

“The only one who names bishops is the pope, the only one who takes bishops away is the pope. Because of this, the only one who controls bishops is the pope.”

Puig said that for the U.S. bishops to have either the authority or autonomy they would need for such a probe “is imagination, it’s fantasy,” because not only were they all named by the pope, but they are investigating fellow bishops – both McCarrick and those who might have covered his tracks.

In his view, Puig said an investigation like this, done without the Holy See, could risk creating a “war” in the bishops’ conference, “because who above all sides? Who is neutral enough to face the problem?”

Typically, an apostolic investigator, or in some cases an investigating team, comes from another country to ensure objectivity. A visitation usually takes place on two levels, he said: the legal level, and the pastoral and political level.

In the case of the U.S. bishops, aside from legal problems,“On the political and pastoral level, it seems to me there is a problem of credibility,” he said. Puig noted that many U.S. prelates have either been implicated in the McCarrick scandal, or they have fires burning in their own backyard.

“For me the decisive thing is that the pope is not taking the initiative,” Puig said. “That is the only possibility to have the authority to get to the bottom of it and carry out their search, in the name of the pope.”

“There are no precedents for this,” he said. “Never have the bishops investigated one another.”

Bishops would also be unable to access Vatican documents, which could prove to be a major issue considering that the only information of interest sits in the archives of Vatican dicasteries.

As an example, Puig noted how there is allegedly a “thick” dossier on McCarrick in the Vatican’s Congregation for Bishops. Archbishop Carlo Maria Vigano, former Vatican ambassador to the United States, referred to the dossier in a bombshell 11-page letter published in August accusing Francis, among others, of knowing about allegations against McCarrick and doing nothing.

“It’s evident that the Congregation for Bishops will not give this material to the American bishops unless the pope authorizes it,” Puig said. “But I don’t see the possibility that the pope and the congregations would leave it freely in the hands of the bishops.”

Neither would anyone be required to cooperate in the investigation, unless it has papal authority, Puig said.

“Why do people normally cooperate with an apostolic visitation? Because they know that behind it is the pope, who has all the power.” If the pope is involved, “you are playing with your soul in some way,” he said, adding that for some, it might seem like not as much is at stake without papal authority.

Noting how many have become impatient for the Vatican to begin a canonical trial on McCarrick’s abuse, Puig said there are no prescribed times for when a trial must begin once a scandal has been unearthed.

The Congregation for the Doctrine of the Faith, which deals with the crime of clerical abuse of minors, currently “has a ton of cases, many cases waiting that they are working on,” and McCarrick is likely at the bottom of the list. He said there’s a possibility that McCarrick’s case is expedited, but there’s no guarantee.

Puig also noted that most of McCarrick’s misconduct happened with adult priests and seminarians, and while there was certainly an abuse of power at play, there were only two cases of minors who alleged having been abused, meaning the congregation, which deals only with delicta graviora crimes, or “serious offenses,” would not oversee the bulk of McCarrick’s misbehavior, perhaps making the case less urgent than others that could also be waiting for trial.

Though at a civil level it might prove difficult to convict McCarrick due to the statute of limitations, the Vatican is able to waive it in certain cases, Puig said, adding that in this sense, the Church has more flexibility than a civil state.

And while McCarrick could face a maximum penalty of being dismissed from the clerical state, “let’s forget about seeing McCarrick enter court in handcuffs. This will never happen,” Puig said.