Parliament in Bangladesh has passed a law allowing the state to appeal any verdict from a special war crimes tribunal.
Demonstrators who had been in Shahbag Square in Dhaka for 13 days burst into cheers as the assembly approved the changes.
They want the death penalty for those accused of committing crimes against humanity during Bangladesh's war of independence from Pakistan in 1971.
Jamaat-e-Islami party assistant secretary general Abdul Quader Mollah was last month sentenced to life in prison for murder, rape and torture.
Law Minister Shafique Ahmed said the amendment will "empower the tribunals to try and punish any organisations for committing crimes during country's liberation war in 1971".
Bangladesh became part of Pakistan at the end of British rule in India in 1947, but broke away in 1971.