LONDON (AP) — Ireland’s government said Wednesday it will take legal action against British authorities over a controversial law that gives some immunity from prosecution for offenses committed during three decades of sectarian violence.

Deputy Prime Minister Micheál Martin said that “after much thought and careful consideration,” the Irish government is launching a legal challenge against the Legacy and Reconciliation Bill, which critics say shuts down access to justice for victims and survivors.

The law, passed in September, stops most prosecutions for alleged killings by militant groups and British soldiers during “the Troubles” — the three decades of violence in Northern Ireland in which more than 3,500 people died.

Those who cooperate with the new Independent Commission for Reconciliation and Information Recovery — loosely modeled on South Africa’s post-apartheid Truth and Reconciliation Commission — can be granted immunity from prosecution. The new law also halts future civil cases and legacy inquests.

Other news Israel summons Irish ambassador over tweet it alleges doesn’t adequately condemn Hamas Ireland’s prime minister condemns anti-immigrant protesters who rampaged through central Dublin 60 years after JFK’s death, today’s Kennedys choose other paths to public service

It was passed despite strong opposition from the Irish government, political parties and victims’ organizations in Northern Ireland.

The 1998 Good Friday peace accord largely ended the decades of violence, and former British Prime Minister Boris Johnson, who proposed the new bill, said it would enable Northern Ireland to “draw a line under the Troubles.”

But those who lost loved ones at the hands of Irish republican and British loyalist militias and U.K. troops say the new law will airbrush the past and allow killers to get away with murder. Dozens of legacy inquests have yet to be heard.

Martin said that even in those cases where immunity isn’t granted, reviews by the independent commission will not be an adequate substitute for police investigations.

Irish Prime Minister Leo Varadkar said the case would be taken to the European Court of Human Rights in Strasbourg, France. It will argue that aspects of the law are incompatible with the U.K.'s obligations under the European Convention on Human Rights.

The United Nations and the Council of Europe backed the country’s position, Varadkar said.

“It is something that we’re genuinely doing with a sense of regret, and would prefer not to be in this position, but we did make a commitment to survivors in Northern Ireland and to the families of victims that we would stand by them,” he said.

U.K. veterans’ groups are among the few organizations to have welcomed the legislation, which lifts the threat of prosecution from troops who served in Northern Ireland.

Rosaleen Dalton, whose father, Sean Dalton, was killed by a booby-trapped Irish Republican Army bomb at a house in Derry in 1988, said the legal challenge gives bereaved families hope.

“People like ourselves and our families have nowhere to go, so just knowing that somebody’s fighting in our corner just gives us some fresh hope and optimism,” she said.

Amnesty International said it was important that the Irish government took its stand.

“The U.K. government doggedly pursued this legislation which shields perpetrators of serious human rights violations from being held accountable,” said Grainne Teggart, of Amnesty International U.K. “This challenge is vital for victims here and around the world who face the prospect of similar state-gifted impunity.”