A UN-backed international court in the Hague ruled on Monday that it has the right to try the alleged killers of former Lebanese Prime Minister Rafik al-Hariri.
The Special Tribunal for Lebanon was set up to investigate the 2005 seafront bombing that killed billionaire businessman Hariri and 21 others, and try the alleged killers.
Defense lawyers for the four suspects argued that the tribunal violated Lebanese sovereignty and could not guarantee them a fair trial.
But the tribunal's judges on Monday rejected those claims and ruled they had jurisdiction on the case.
Hariri's killing plunged Lebanon into years of political turmoil, culminating in sectarian violence in May 2008 that pushed the country to the brink of civil war.
The international court is controversial in Lebanon. Although it was set up with the support of the Lebanese government five years ago, it is opposed by Hezbollah, a political party and guerrilla group of which the four suspects are members.
The current Lebanese government, dominated by the Iranian-backed Hezbollah and its political allies, has told the court the suspects cannot be found. The court plans to try the suspects, all Lebanese nationals, in absentia and has set a provisional trial start date of 25 March next year.
Antoine Korkmaz, a defense lawyer appointed to represent one of the suspects, said the tribunal had been created illegally by the United Nations Security Council and was interfering with Lebanon's domestic affairs.