Pope Francis has issued a landmark decree making bishops directly accountable for sexual abuse or covering it up, requiring clerics to report any cases to Catholic Church superiors.
It also allows anyone to complain directly to the Vatican if needed.
Tackling sexual abuses that have battered the Catholic Church's reputation has been a major challenge for Francis since his 2013 election, with victims demanding a crackdown on bishops at the diocese level accused of concealing or mismanaging cases.
The papal change in church law, covering abuse of children and adults alike, also obliges every diocese worldwide to set up simple, accessible reporting systems and encourages local churches to involve lay experts in investigations.
Francis's edict obliges the world's 1 million priests and nuns to report all suspicion of sexual abuse by clerics of any level. Before, it was just a mtter of individual conscience as to whether to report cases.
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.
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Former US Cardinal Theodore McCarrick was expelled from the Roman Catholic priesthood last February after he was found guilty of sexual crimes against minors and adults, including forcing seminarians to sleep with him.
"We have said for years that priests should follow certain strict rules, so why should bishops and other members of the church hierarchy be exempt?" said Cardinal Marc Ouellet, head of the Vatican's Congregation for Bishops.
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.
But the decree does not alter Vatican policy that clerics should follow local law as to whether they are mandated to report alleged sexual abuse to civil authorities.
Victim's groups and their advocates have called for the Vatican to make reporting of suspected abuse to police mandatory but the Holy See says church law cannot override local civil law because the latter varies around the world.
The papal edict says 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".
Maltese Archbishop Charles Scicluna, the Vatican's top sexual crimes investigator, told reporters the purpose 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.
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The 19-article decree, called Vos Estis Lux Mundi (You Are the Light of the World), raises to 18 from 16 the age of adulthood in cases of sexual abuse. It also covers possession of child pornography.
The edict came three months after Francis summoned the heads of all national bishops conferences to Rome in February for a crisis summit on sexual abuse.
A spate of abuse scandals has battered church credibility around the world and forced some dioceses to declare bankruptcy because of billions of dollars paid in settlements with victims.
The decree sets time limits for local investigations and the Vatican's response to them, and allows for retroactive reporting.
The decree further says local clerics cannot order those who report abuse to remain silent and that senior bishops should make provisions to prevent documents from being destroyed by subordinates if needed.
Many local Catholic Churches have been hit by sex abuse scandals since they erupted on a large scale in Boston in 2002 with revelations that church leaders there had moved sexual abusers from parish to parish instead of defrocking them.