A two-year grand jury investigation in Pennsylvania resulted in what the state's attorney general, Josh Shapiro, called "the largest, most comprehensive report into child sex abuse in the Catholic Church ever produced in the United States."

But the report, released Tuesday, was not the first. In 2002, The Boston Globe revealed that Catholic authorities in the Boston Archdiocese had engaged in a massive cover-up of sex crimes committed by area priests, and investigations in other parts of the country have since uncovered similar patterns of sexual abuse by members of the Catholic clergy. The ongoing scandals amount to a deepening church crisis.

"Each new report of clerical abuse at any level creates doubt in the minds of many that we are effectively addressing this catastrophe in the Church," Cardinal Sean O'Malley, the archbishop of Boston, warned last month.

His statement came in the aftermath of what the Washington Archdiocese called a "credible and substantiated" allegation leveled against Cardinal Theodore McCarrick, the former archbishop of Washington. O'Malley cautioned that a failure to take action in such cases "will threaten and endanger the already weakened moral authority of the Church."

History, law and doctrine all contribute to the continuing failure of Catholic authorities to recognize and respond more effectively to sexual abuse scandals.

Catholics trace their church origin back 2,000 years to the early Christian communities established by Jesus and his Apostles, and Roman Catholic doctrine has long emphasized continuity. For an institution so rooted in tradition, change can be difficult.

The pope and his bishops are officially considered "vicars and ambassadors of Christ" on Earth, a status that accords them special authority and privilege. A notable feature of the Pennsylvania grand jury investigation, however, was the extent to which it found that the bishops in each diocese were implicated in the crimes.

"The abuse was occurring not only by its own people, but on its own property," the grand jury reported. "Children were raped in places of worship, in schools, and in diocesan owned vehicles, and were groomed through diocesan programs and retreats. The bishops weren't just aware of what was going on; they were immersed in it. And they went to great lengths to keep it secret."

The report's emphasis on bishop culpability distinguished it from some earlier investigations of clerical abuse, which focused more narrowly on the behavior of individual priests. In 2002, after The Boston Globe revelations, U.S. bishops meeting in Dallas approved a set of procedures to ensure that allegations of abuse by priests would be forwarded to civil authorities. The Pennsylvania grand jury investigation demonstrated the inadequacy of that approach.

"This is incredibly uncomfortable for the Catholic Church," says Terence McKiernan, co-founder and president of BishopAccountability.Org, which tracks sex abuse cases in the Catholic Church. "It's always dealt with these problems as problems with the priests, when it dealt with them at all. Now the whole system is on view."

Pope Francis himself has been challenged by the widening abuse scandal, despite his own efforts to deal with it. In 2014, he appointed a Pontifical Commission for the Protection of Minors under the leadership of Cardinal O'Malley, and a year later, he approved the creation of a tribunal to investigate and judge bishops accused of protecting abusive priests. Earlier this year, Francis acknowledged that he had made "serious mistakes" in his initial response to clerical abuse allegations in Chile, and he accepted the resignations of three Chilean bishops at the center of the scandal.

But the Vatican has been slow in implementing the recommendations of the Pontifical Commission, and the proposed tribunal for bishops was not established. In Chile, authorities this week carried out a series of raids at Catholic church offices, looking for evidence they said the Chilean church had not produced.

'Rules of the land didn't really apply'

One issue highlighted by the ongoing clerical abuse scandal is a possible conflict between canon law and civil law. Catholic authorities in the past have sometimes argued that their own rules and institutions are adequate to deal with wayward clergy.

"Until very recently, there was a sense among church officials that they lived and worked in a kind of separate preserve, and even that the rules of the land didn't really apply to them," says McKiernan.

Until very recently, there was a sense among church officials that they lived and worked in a kind of separate preserve, and even that the rules of the land didn't really apply to them.

Terence McKiernan

Such attitudes enabled church authorities in some cases to ignore abuse allegations if they were otherwise satisfied with a priest's behavior, or perhaps to transfer an accused priest to another parish rather than turn him over to law enforcement.

Church rules now obligate bishops to forward any evidence of sexual abuse by priests to civil authorities, but canon law and procedures are still relevant. Bishops who overlook evidence of abuse may not themselves be subject to criminal proceedings, which means it will be up to church authorities to deal with them. In addition, some situations are beyond the scope of civil law enforcement.