This time, at least, the Special Tribunal for Lebanon managed to navigate through an official’s resignation by immediately appointing a successor. The tribunal’s president, Antonio Cassese, stepped down this week, to be replaced by Sir David Baragwanath of New Zealand. The smoothness of the transition aside, Cassese’s departure with a trial looming did little to bolster the institution’s credibility.

In recent months, the debate over the special tribunal has been largely defined by those yearning for its failure. Even the prime minister, Najib Mikati, is in a bind. He went far in promising that his government would approve funding for the tribunal, only to see this turned against him by Hezbollah and Michel Aoun. What the outcome will be is anybody’s guess, but Mikati will probably opt to delay the issue indefinitely, averting a showdown in which he is bound to be humiliated. He may be wagering that an international community incapable of approving a Security Council resolution condemning the savagery of Bashar Assad’s regime in Syria, will be equally unlikely to punish Lebanon for failing to honor its financial obligations.

On the side of those who endorse the tribunal, present company included, there has mainly been uncritical acquiescence to whatever the institution does. Some cracks in confidence have started to appear, not least after it became known that the prosecution would not be taking up several bomb attacks committed in 2005, including those against journalists May Chidiac and Samir Kassir. However, the March 14 coalition continues to view the tribunal as its principal weapon against the majority.

Tactically, this is understandable. But for those more interested in whether the special tribunal represents a qualitative judicial achievement that enhances the rule of law in Lebanon, the picture is more blurred. Six years after the assassination of the former prime minister, Rafik Hariri, such an ambition has evaporated. Perhaps that was to be expected, but it has also been facilitated by long, unjustified, and damaging delays in the investigation of the crime.

The indictments issued by the tribunal offer us, bluntly, a crime without an articulated motive. It is embarrassing that after six years of investigation, only four suspects, all active at the operational level, have been named. This may change, indeed it must change if the prosecutor is to strengthen his case. In practical terms this requires indictments of those who ordered Hariri’s elimination, with an explanation for why they did so. And yet something tells us that this may be it for now – with the prosecutor, Daniel Bellemare, hoping to use the initial indictments as a wedge for further indictments.

Motive is the key to most crimes. Detlev Mehlis, the first head of the independent investigative commission of the United Nations, concluded that Hariri had been killed for political reasons. He and his allies were on the verge of winning a parliamentary majority in the summer 2005 elections, a point acknowledged by Syria’s Lebanese allies. The former prime minister himself was telling foreign envoys that he would gain a majority whichever election law was adopted.

When you put this together with what the Syrians were then saying, a hypothesis becomes clearer. A Syrian friend familiar with regime thinking in Damascus informed me in January 2005 that Assad intended to “respond to” Security Council Resolution 1559, which, among other things, called for Syria’s army to be removed from Lebanon. Syrian forces would be redeployed in the direction of the Syrian border, he said. But no one was talking of a full withdrawal.

The Syrians had a good reason for imagining that this ploy would work. In early 2005 the United States was willing to advance in stages on a withdrawal. In the words of the former ambassador in Beirut and current assistant secretary of state for Near Eastern affairs, Jeffrey Feltman, Washington sought “to avoid allowing the perfect to be the enemy of the good.” In other words, the Americans considered a partial Syrian pullback preferable to none at all. In his speech before Syria’s parliament in early March 2005, three weeks after Hariri’s murder, Assad behaved precisely according to that playbook. He declared that Syrian troops would soon start moving toward the border, though he did not say that they would actually cross it.

Here is probably what the Syrians were thinking. At some point in late 2004, they concluded that an election victory for Hariri and his comrades represented an existential threat to the Syrian order in Lebanon. Hezbollah concurred, anticipating that a Hariri government would undermine the substantial military and political advantages the party enjoyed under Syrian rule. A decision was taken to get rid of the former prime minister, to be followed by steps suggesting that Syria would implement Resolution 1559 and move all its forces into the Bekaa Valley. This injected a useful ambiguity into the equation, since it could be depicted as falling in line with the Taif Accord (which even Walid Jumblatt preferred to hold up at Syria instead of Resolution 1559). With Hariri gone, the Syrians would win the elections hands down, bring in a friendly government, and under the rubric of Taif negotiate with that government a continued Syrian presence in Lebanon, circumventing Resolution 1559.

What spoiled the scheme? We have to assume growing Arab and international pressure on Syria, but also the mass demonstration of March 14, 2005, which convinced Assad that his plan had backfired. He now faced a united and mobilized Sunni community, working in tandem with a unified Christian community and the Druze. The elections, Assad could plainly see, would lead to the very outcome that the Syrian president had sought to avert. He apparently concluded that it was better to bring his troops home before that happened.

Is this interpretation debatable? Sure, but until now the Special Tribunal for Lebanon has little enriched the conversation. We have suspects, but no hint as to their purpose. Bellemare may propose an explanation by indicting new figures, or he may outline his thinking in court. But without new suspects his case will be weak, and many of us will be even more persuaded that the tribunal has let us down.

Michael Young is opinion editor of THE DAILY STAR and author of “The Ghosts of Martyrs Square: An Eyewitness Account of Lebanon’s Life Struggle” (Simon & Schuster). He tweets @BeirutCalling.