WASHINGTON - A long-awaited study on clergy sex abuse in the Roman Catholic Church prepared for the U.S. Conference of Catholic Bishops asserts that the explosion of cases had been part of a broader trend toward sexual and social freedom that emerged 40 years ago - and that the crisis is largely over.

Beginning in the 1960s, "the increased deviance in society at large intersected with the vulnerabilties of some priests," Karen Terry, the principal author, said at a news conference Wednesday for the release of the 142-page report.

Priestly celibacy "was not a cause," she said.

She added later that the abuse scandal was not a compelling reason for the Catholic Church to lift its celibacy requirement for clergy.

Commissioned four years ago by the bishops from the John Jay College of Criminal Justice in New York, the report looked at the sexual abuse of minors by clergy between 1950 and 2010, a period during which about 5 percent of diocesan priests were credibly accused of child molestation. The cost to the nation's dioceses has been estimated at $2 billion.

The researchers found that more than 90 percent of the known cases had occurred before 1990. The incidence rose steadily in the 1960s, reached a peak in the '70s, and was declining markedly by the mid-'80s - correlating, Terry said, with a tumultuous time for American morality in general.

Within hours of its release, the report was stirring controversy. It took a largely sympathetic view of bishops who reassigned abusive clergy to parishes after counseling, and put little blame on the hierarchy for the problem of repeat offenders.

David Clohessy, executive director of the Survivors Network of those Abused by Priests, called the study inadequate and self-serving.

"This is one more effort by the bishops to say [clergy sex abuse] is ancient history and 'not our fault,' " he said. "To say it was caused by culture of a couple of decades ago is just ludicrous."

At the news conference, Bishop Blasé Cupich of Seattle, chairman of the conference committee that oversees sex-abuse matters, referred to recent grand jury allegations that the Archdiocese of Philadelphia had kept dozens of credibly accused priests in ministry. That, he said, would be an "anomaly" and not typical of most dioceses.

He conceded, however, that sex abuse "was sometimes very badly handled" by many dioceses over the years. "The shame of failing our children," Cupich said, "will remain with us for a long time."

The report noted that most bishops had failed to follow a set of guidelines that the conference had agreed upon in 1992. It called for church officials to respond promptly to any abuse report; remove the alleged offender from ministry; comply with local laws and cooperate with law enforcement; and reach out to the victim and his or her family, as well as to the affected parish.

"Much of this was not done," the researchers found.

Part of the reason for the bishops' inadequate response might have been the sudden flood of abuse reports in the 1990s, according to the study. Between 1950 and 1985, only 840 abuse complaints were made to dioceses, and many of those were lodged by parents to pastors. From 1990 to 1998, the total jumped to 3,700. Those complainants often were adult victims angry and threatening to sue.

Many bishops retreated from the guidelines in the face of the sudden increase in allegations, but that only made matters worse, the researchers stated. After news reports in 2002 that dozens of abuser priests in the Archdiocese of Boston had been allowed to remain in parish ministry, the scandal spread to nearly all 195 dioceses in the nation, and remains a cloud over many.

At its semiannual meeting in Dallas that year, the bishops conference called for adoption of a charter that spelled out the steps a bishop must take when presented with an abuse allegation against a priest. At that meeting, the bishops called for the "causes and context" study, which was commissioned only in 2007.

Among the report's more controversial features is its narrow definition of pedophilia. It describes the disorder as a fixation by an adult solely on a prepubescent child, whom it defines as 10 years of age and younger. As such, the report concludes, only 5 percent of priests who abused minors were "pedophiles," because most offenders also abused older children or had sexual relations with adults. Priests who molested prepubescent children as well as teens are called "general offenders."

Terry said the report's pedophilia definition was not John Jay's but was derived from a variety of studies.

The study also found that 80 percent to 85 percent of the victims of sexual assault by priests were boys. Nevertheless, it said, it could find no compelling evidence that clergy who had sexual relations with other males before or during seminary were likelier to abuse minors.

There was - and remains - no easy way to identify candidates for priesthood who might molest children, the John Jay team concluded.

"Priests who sexually abused minors did not differ significantly from other priests passed on psychological or intelligence tests," the report stated. It noted, however, that they typically had "vulnerabilities, intimacy deficits, and an absence of close personal relationships before and during seminary." Many abusers grew up in families where sexuality was never discussed, the study found.

Those who were sexually abused in childhood or came from dysfunctional families were also likely to seek sexual gratification from children, the report said. It noted, however, that those patterns were typical of sexually abusive men in general.

The researchers found that many bishops reached out to help abusive priests, most often by sending them to treatment. Throughout the 1970s and early '80s, psychologists and other therapists took an "optimistic" view of therapy's ability to mend an abuser's ways, but bishops began having increasing doubts about therapy's effectiveness around 1985.

The hierarchy, however, was exceedingly slow to grasp the psychological damage of sexual abuse - especially by a trusted adult.

"Diocesan leaders responded to acts of abuse," the report asserted, "but with a focus on the priests and not the victims."

Contact staff writer David O'Reilly at 215-854-5723 or doreilly@phillynews.com.