"I welcome the new motu proprio from Pope Francis with its clear procedures for the accountability of bishops and the protection of those who report abuse becoming the universal law of the Church", tweeted Bishop John Stowe of Lexington, Kentucky.
The new norms cover internal Catholic Church procedure, not the issue of reporting abuse or cover-up to civil authorities, and represent a top-down imposition which must be followed by all dioceses.
In addition, by June 2020, each diocese must set up "stable and easily accessible systems for submission of reports" by the public, although the design of such confidential systems or offices was left to the discretion of the local church, according to the pope's decree.
It calls for whistleblower protection, saying bishops with conflicts of interest should recuse themselves from investigations and that bishops can also be held accountable for abuse of power in sexual relations with adults.
The law defines the crimes that must be reported as: performing sexual acts with a minor or vulnerable person; forcing an adult "by violence or threat or through abuse of authority, to perform or submit to sexual acts", and the production, possession or distribution of child pornography.
The new rules come into force on June 1 and will be re-evaluated after a three-year trial period.
Francis told 850 superiors of religious orders gathered at the Vatican for the triennial assembly of the International Union of Superiors General, the main umbrella group of nuns, that theirs is a vocation of service, not servitude.
The Vatican has long argued that different legal systems in different countries make a universal reporting law impossible, and that imposing one could endanger the church in places where Catholics are a persecuted minority.
Francis's edict obliges the world's one million priests and nuns to report all suspicion of sexual abuse by clerics of any level.
The decree also allows victims or their representatives to report alleged abuses by bishops directly to the Vatican or a Vatican ambassador, bypassing diocesan procedures that have been discredited by multiple instances of cover-ups.
The norms "apply without prejudice to the rights and obligations established in each place by state laws, particularly those concerning any reporting obligations to the competent civil authorities".
In the past, some people may have thought they were protecting the church by remaining silent, but that behavior was never acceptable, Archbishop Charles Scicluna of Malta, adjunct secretary of the Congregation for the Doctrine of the Faith, told reporters.
Maltese Archbishop Charles Scicluna, the Vatican's top sexual crimes investigator, told reporters the objective of that section was to mandate priests and nuns to report abuse within the church even in countries - including several in Latin America - where they are not obliged by civil law to do so. And it outlines internal procedures for conducting preliminary investigations when the accused is a bishop, cardinal or religious superior. And in a novelty, the law requires that if victims request it, they must be told of the outcome of the investigation - again a response to complaints that victims are kept in the dark about how their claims were handled. The accusation must be notified only if formal proceedings are opened.
This is a major step forward for the Vatican.
The Pope promised in February to take concrete action to tackle abuse.