The Senate (upper house) of the Liberian Parliament voted to establish a special court to try crimes committed during the two civil wars, local media reported.
The document was reportedly approved by 28 of the 29 members of the Senate.
The court will be tasked with prosecuting those most responsible for war crimes and crimes against humanity committed between 1989 and 2003, media said.
During his swearing-in speech in January, Liberian President Joseph Boakai said that his government would explore the possibility of opening a "war and economic crimes court" for "those who bear the greatest responsibility for war crimes and crimes against humanity."
In March, the Liberian House of Representatives (lower house) passed a bill to establish a war crimes court, with 42 out of 72 lawmakers voting in favor.
The Senate has made some changes to the parliamentary bill, which must now be reconciled with the lower house and then sent to the president for his signature.
The Liberian Truth and Reconciliation Commission recommended the creation of the court in 2009, and the US announced its intention to fund the institution in 2022.