Twenty-three years is an unusual definition of efficient justice.

Yet that is the striking backdrop to the UK Supreme Court’s recent decision in the AXA case.

The case stems from a Group Litigation Order (GLO) established back in 2003 to coordinate claims by companies challenging aspects of the UK tax regime.

AXA was not selected as a test case. Its claim was stayed while other proceedings made their way through the courts – a process involving multiple levels of the UK judiciary and the European courts.

The GLO may have avoided multiple parties litigating the same questions separately, but for an individual claimant it also meant years of waiting.

That exposes a tension in how we think about the efficiency of collective litigation.

A procedure can be efficient for the court system while being remarkably inefficient for the individual claimant. Reducing the number of hearings and avoiding duplication is valuable, but so is reaching a resolution within a reasonable timeframe.

From a claimant’s perspective, a dispute that remains unresolved for years carries its own costs – financial, commercial and simply the uncertainty of not knowing when the matter will finally end.

The difficulty is that these different forms of efficiency do not always point in the same direction. What may be the most efficient way for a court to determine a common issue may not be the quickest route for every claimant whose case depends on that issue.

The AXA litigation therefore raises a broader question about how we measure the success of GLOs.

If collective litigation is intended to deliver efficient justice, perhaps efficiency should be measured not only by how much litigation is avoided, but also by how long claimants have to wait.

Perhaps, then, the more useful question is not simply whether collective litigation is efficient, but efficient for whom?

After all, justice may be collective. The waiting is not.