Retrospective Delay Analysis: Still Cause and Effect, Even When You Start With the Effect
There’s been a quiet shift in how some delay practitioners interpret “cause and effect” analysis—and not always for the better.
In some corners, there’s a misconception that starting with the effect (the delay) somehow breaks the logic of a proper analysis. But let’s be clear: retrospective analysis that begins with what actually happened and traces it back to the true cause is still a cause and effect analysis, just grounded in fact rather than theory.
The Courts agree.
In V601 Developments Pty Ltd v Probuild Constructions (Aust) Pty Ltd [2021] VSC 849, Justice Digby affirmed the principle with clarity:
“A cause and effect analysis is, in principle, a sound method of analysis, provided it is applied in a factual and logical manner.”
Importantly, this was in the context of rejecting a prospective, model-driven approach which lacked logical coherence and failed to reflect what actually happened on site. In other words, Digby J wasn’t just endorsing any “cause and effect” method, he was reinforcing the need for real-world, evidence-based analysis.
The same message came through, perhaps more sharply, from Justice Hammerschlag in White Constructions Pty Ltd v PBS Holdings Pty Ltd & Anor [2019] NSWSC 1166. That case dealt with the use of complex theoretical models to predict delays, models that were divorced from the facts on the ground.
Justice Hammerschlag had this to say:
“A critical path analysis is only as good as the data that goes into it and the assumptions on which it is based… the critical path is not a matter of theory; it is a matter of fact.”
In short: you cannot build a credible delay claim on hypotheticals and assumptions. The courts are looking for clear, logical links between what happened and why it happened. That’s cause and effect.
Now, in practice, forensic delay analysis often starts with the known event—the effect. A delay occurred. It’s documented. The project slipped. From there, the analysis works backwards: what caused it? Was it a variation? A late approval? A sequencing change? This may feel like “effect and cause,” but in legal and logical terms, it’s just the reverse process of establishing cause and effect—backwards or not, it’s the same analytical structure.
What matters is that the link between the two is real, evidenced, and structured in a way the court can follow. That’s the essence of what both Digby J and Hammerschlag J were saying. Forget the fancy modelling. Forget the forecasted paths that never materialised. If it didn’t actually happen, don’t build your claim on it.
Because when your analysis gets tested—and it will—it’s not just about methodology. It’s about credibility.
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