The opposition and NGOs have previously denounced the amnesty as a move by the government to shield the police and military officers responsible for the killings from justice.
Chad's government-appointed parliament, the National Transitional Council, adopted the law with 92.4 percent of members voting in favour, said National Reconciliation Minister Abderaman Koulamallah.
The law is part of a commitment to "national reconciliation" and applies "to all Chadians, civilians and soldiers" according to the text seen by AFP.
Hundreds of demonstrators poured onto the streets of the semi-desert country on October 20, 2022, mainly youths protesting against a move by military president Mahamat Idriss Deby Itno to cling to power.
About 50 people, according to the government, or at least 300 according to the opposition and independent observers, were killed by police and military fire in the capital N'Djamena.
'Unfair trials'
After the demonstrations on what the opposition calls "Black Thursday," the regime said 621 youths, including 83 minors, were detained at an infamous desert jail at Koro Toro, 600 kilometers (370 miles) from the capital.
Most were convicted and sentenced to prison in a mass trial, before being pardoned by Deby.
Local and international NGOs as well as UN-mandated experts estimate that 1,000-2,000 were arrested. Dozens if not hundreds of them have since disappeared.
"Despite the authorities' immediate promise of an inquiry, all we have seen up to now is unfair trials behind closed doors of demonstrators and the absence of serious investigations into the alleged perpetrators of the killings," Amnesty International said in October 2023, on the one-year anniversary of the protests.
Mahamat Deby, a general, was proclaimed transitional president by the army on April 20, 2021 following the death of his father, Idriss Deby Itno, who had run Chad as a dictator for 30 years and was killed by rebels while visiting frontline troops.
Deby had promised elections within 18 months, but after that date passed he put off a vote for another two years, sparking the deadly protests.
A referendum on a new constitution is scheduled for December 17 and is due to set the stage for "free" elections and a return to civilian rule.
The vast majority of opposition parties are calling for a boycott of the vote.
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