The allegation that Cardinal Theodore McCarrick sexually abused a teenager is a bombshell for the Catholic Church in America.

McCarrick has stepped down from active priestly ministry at the direction of the Holy See, after an initial investigation judged the allegation to be "credible and substantiated."

What does that mean, and what might be next for McCarrick?

Any allegation of sexual abuse by a member of the clergy is a serious tragedy, but an allegation against a prominent cardinal, even a retired one, can be devastating for lay Catholics and clergy.

The allegation against the cardinal is that in 1971, then-Monsignor McCarrick fondled the genitals of a 16-year-old boy in the sacristy of St. Patrick's Cathedral in New York, while measuring the boy for a cassock. McCarrick is alleged to have fondled the same boy in a sacristy restroom the next year, according to the New York Times.

As emeritus Archbishop of Washington, D.C., previously Bishop of Metuchen and Archbishop of Newark, McCarrick occupied a place of prominence in the US Church. It would be difficult to find any prominent East Coast cleric who has not been photographed next to a smiling McCarrick, who has been a visible presence in the Church even in his late 80s.  

Despite the public persona of an affable bishop, equally at home preaching before a packed cathedral or engaging a room full of donors, rumors have swirled around him privately for years.

Several American priests have spoken to CNA in recent days, noting the uncomfortable reputation McCarrick had for "snuggling," and his insistent affection for seminarians. Priests in his orbit have recalled the nicknames used in some clerical circles, the oft-mentioned "Uncle Ted" and the uncomfortable moniker "Teddy Bear."

Statements issued June 20 from the Archdiocese of Newark and the Diocese of Metuchen confirmed that McCarrick has faced previous allegations of sexual misconduct, albeit with adults, which ended in settlements. That fact seems to lean heavily against his defense in this case, despite his claim of innocence.

This dissonance between public persona and private reputation makes an especially difficult case for the Church to handle, in Rome and in the United States.

As Archbishop of Washington, Cardinal McCarrick was a leading participant in the development of 2002's Dallas Charter, which established procedures for handling allegations of sexual abuse.

The reforms he helped to adopt have now become the measure by which he will be judged. In fact, the extent to which the full rigor of those norms is applied to his case could also become the measure against which their integrity is assessed.

Under canon law, it is the pope alone who has the right to judge cardinals (even retired ones) in matters of penal law. According to a June 20 statement from the Archdiocese of Washington, Pope Francis delegated Cardinal Timothy Dolan of New York to conduct at least the initial stages of the investigation, which have now been concluded.

Whenever there is an allegation of clerical sexual abuse against a minor, canon law requires that the diocese concerned hold a "preliminary investigation." That process is meant to establish if the accusation has "the semblance of truth," or, in the language of the Charter, is "credible."  

The standard of proof required at that phase of the process is very low- requiring only that the accusation not be found manifestly false or frivolous. But what that investigation discovers determines what happens next.

In the United States, following the Dallas Charter, an assessment of the investigation is usually conducted by a diocesan review board. Review boards are quasi-independent bodies made up of legal experts, clergy and independent advisors appointed by the bishop.

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If the review board concludes the allegation has the semblance of truth, and the bishop agrees, the matter is ordinarily referred to the Congregation for the Doctrine of the Faith in Rome. Since cases involving cardinals are reserved to the pope personally, the case of Cardinal McCarrick was likely forwarded directly to the pope, with some input from the CDF.

In cases involving priests or deacons, if the CDF finds the results of the preliminary investigation suggest further investigation, it has several options.

If the allegation seems well-substantiated, it can refer the matter back to the diocese, to be handled by a canonical trial, or by an expedited process ending in an extrajudicial decree. The CDF can also convene an extrajudicial process or a trial in Rome, handling the matter directly. This is the typical approach in cases which are not clear, or which, for some reason, are particularly contentious or high-profile.

Subsequent to that process, if the cleric is found guilty, the Church may impose the penalty of laicization, permanently removing the cleric from clerical life and ministry, or, taking into account factors including the cleric's age and health, impose some other penalty. A cleric found to have committed the crime of sexual abuse can never be returned to ministry.

According to the Archdiocese of New York's statement, following the preliminary investigation, the Archdiocesan Review Board found the allegation against Cardinal McCarrick to be both "credible" and "substantiated." Taken at face value, this sounds very bad for Cardinal McCarrick's case.

In fairness, it should be noted that the norms for diocesan review boards allow for significantly different processes and standards in different places, that the procedural and evidentiary norms required in a canonical trial are more stringent, and that the right of defense- an essential part of any legal process- is more robustly defined in a canonical trial.

What happens next will tell us much about how Rome views the credibility of the allegation against Cardinal McCarrick.

In the very rare instances in which archbishops (let alone cardinals) have been personally accused of sexual abuse, full canonical trials have been held at the Apostolic Tribunal of the CDF in Rome, essentially the highest judicial court the Church has. If Cardinal McCarrick's case is handled by an extrajudicial process in New York, this would suggest overwhelming confidence by Rome in the credibility of the accusation.

It is important, as with any legal system, that the canonical process be allowed to run its course. It is also important that Cardinal McCarrick be given every proper chance and means to defend himself and assert his innocence as part of that process.

It is also possible that, at age 87, Cardinal McCarrick will not face a trial or an extrajudicial process.

In the meantime, the fact that the Archdiocese of Newark and the Diocese of Metuchen confirmed that there have been previous complaints and settlements because of McCarrick has already caused scandal.

An important question about his ecclesiastical career has also begun to be asked: how was McCarrick allowed to continue for so long in office, and then continue in public ministry after retirement, when Church authorities knew of these settlements?

McCarrick's former dioceses have been swift to insist that they have never previously received any allegations of sexual abuse of minors. But, as now seems clear, they were aware of credible allegations of sexual misconduct against the cardinal. Some commentators have wondered if Church authorities presumed that so long as no children were involved, there was no obligation to curtail his ministry.

This is not a dry question of past failings by previous administrations: close personal associates of Cardinal McCarrick continue to hold leadership positions in American diocesan curias.

It might be asked whether individuals who could have known - indeed can be reasonably expected to have known - about McCarrick's behavior, or at least the persistent rumors of it, remain in positions where they will be responsible for assessing and disciplining clergy following allegations of misconduct.

Questions will likely be raised about what these men knew, what they heard, what they did about it and when. Anything less will likely leave some Catholics wondering what else might lurk in the shadow of this scandal.

Hard questions may also soon asked of the other three cardinals in this story: Dolan, Tobin, and Wuerl. They are likely to be asked when they first learned of allegations against Cardinal McCarrick. Cardinals Tobin and Wuerl, especially, might be asked if it would serve the public interest to make clear when they discovered that their mutual predecessor (once removed, in Tobin's case) had been the subject of sexual misconduct complaints serious enough to prompt legal settlements - and whether they raised questions about his continued public life and ministry during retirement.

While leaving all necessary space for the canonical process concerning the specific allegation involving a minor, the extent to which the cardinals are willing to engage publicly about what they know about the other complaints against Cardinal McCarrick, when they knew it, and what they did, or did not do, about it, could also bear heavily on the credibility of the American hierarchy.

For Pope Francis too, the McCarrick scandal is a serious test. Following allegations of sexual misconduct, the late Cardinal Keith O'Brien, formerly of St. Andrews and Edinburgh, died in disgrace and exile. While he was not formally stripped of his title, in March 2015, Francis accepted his resignation of the rights and privileges of a cardinal.

Having already suspended McCarrick from public ministry for the duration of the canonical process, the steps Pope Francis takes against him at the conclusion of the process - especially taking into account the previous accusations and settlements - will be closely analyzed.

Following on the heels of the much-criticized handling of the sexual abuse scandal in Chile, both the Holy See and the American bishops will be acutely aware that such a high-profile case needs to be handled very carefully. To stop the McCarrick scandal before it becomes a crisis, the margin for error is very slim.