The European Union on Tuesday said experts had agreed on the "legal foundations" for a special tribunal to try Russia over the war in Ukraine.
Proposals for establishing a court to hold Russia accountable over its invasion were floated more than two years ago.
But wrangling over the legal basis for the tribunal and how it would work has meant progress on establishing it has been painfully slow.
The return of US President Donald Trump to the White House appears to have sped up efforts, as European officials fear his plans for a peace deal could mean Moscow escapes justice for good.
The EU said experts from 37 countries meeting in Brussels had "laid down the legal foundations for the establishment of a Special Tribunal for the Crime of Aggression against Ukraine".
They also set out the key elements of the legal text that would govern how the court functions, Brussels said.
"When Russia chose to roll its tanks over Ukraine's borders, breaking the UN Charter, it committed one of the gravest violations: the Crime of Aggression," European Commission president Ursula von der Leyen said.
"Now, justice is coming. Justice for Ukraine."
EU justice commissioner Michael McGrath said that some technical work remained to draw up a final draft but he hoped it would be concluded in the near future.
While talks have dragged on over the tribunal, the International Criminal Court (ICC) in March 2023 issued an arrest warrant for Russian President Vladimir Putin over the abduction of Ukrainian children.
But the special tribunal is specifically intended to try Russia for the "crime of aggression", for which the ICC does not have jurisdiction.
In a bid to hold Russia accountable, Ukrainian and international investigators have continued efforts to document thousands of cases of abuses committed during the war.
Kyiv has said that it is probing over 140,000 cases of potential war crimes in the country.
In a related push to try to make Russia pay for the damage it has wrought in Kyiv, the EU also proposed Tuesday joining possible talks on an "International Claims Commission" for Ukraine.