The West African nation's two civil wars, notorious for their brutality and use of child soldiers, left an estimated 250,000 people dead between 1989 and 2003.
Despite international and domestic demand, Liberia has yet to try anyone for crimes committed during the bloody conflicts, which resulted in massacres, mutilation, rape and cannibalism.
The Senate on Tuesday backed a resolution supporting the establishment of a war and economic crimes court, after the lower house of parliament voted in favor of its creation last month.
Twenty-eight senators voted for, one abstained and one vote was not cast due to a vacant seat.
The resolution will now return to the lower house to agree changes before it is sent to President Joseph Boakai for approval. A bill would then be drafted and debated by both houses.
During his swearing-in speech in January, Boakai said 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."
The United States has hailed steps towards creating the court.
"Liberians have waited far too long to see justice for the horrific abuses they suffered in the country's two civil wars," US Ambassador at large for Global Criminal Justice Beth Van Schaack said in an open letter to Liberians in March.
A Truth and Reconciliation Commission (TRC) in 2009 recommended the establishment of a war crimes tribunal, but this has largely gone unheeded, particularly in the name of peacekeeping as a number of accused warlords remained influential in their communities.
FILE—Presidential candidate and former warlord Prince Johnson, campaigns in the village of Demeh in Bomi County, Liberia, September 14, 2011.
One of the most prominent of these is current senator Prince Johnson, who was shown in a video sipping beer while his men tortured then-president Samuel Doe to death in 1990.
Johnson had until recently been a vocal opponent of establishing the war crimes court, but on Tuesday signed in favor of the resolution.
While no trials have taken place within Liberia, a number of convictions have been secured abroad.
A French court at the end of March handed former rebel commander Kunti Kamara a 30-year prison sentence for violence against civilians and complicity in crimes against humanity during the first civil war.