Critical Paths and Critical Thinking: Lessons for Delay Experts from Santos v Fluor
The recent decision in Santos Limited v Fluor Australia Pty Ltd [2025] QSC 184 is one of the clearest reminders yet of what courts expect from delay and programming experts. It shows that credibility is earned through structure, logic, and transparency — not volume or software output.
Both parties presented programming experts. One used an approach that compared what was planned with what was actually built across defined windows of time. The other relied on abstract reasoning about near critical paths and what might have happened if certain delays were removed.
The referees preferred the first approach. The Court agreed and confirmed that the reasoning was sound, factually supported, and consistent with accepted practice. The other expert’s analysis was described as flawed and unsafe.
The problem with near critical path reasoning
The referees said the losing expert’s analysis assumed that if one delay was removed, other activities would have caused delay anyway. In other words, they claimed that the project would still have been late even if the main cause of delay had not occurred.
The referees found this was not a safe assumption. Removing one delay can change the sequence of work and shift the critical path entirely. Delay analysis cannot rely on static logic or wishful counterfactuals. The Court agreed, finding that the referees were entitled to reject this reasoning.
Lesson: delay analysis must reflect how projects behave in reality. A critical path moves when conditions change. If the expert cannot show what would actually have happened, the analysis has no value.
Why the as built in windows method was preferred
The referees found that the as built in windows approach clearly linked cause and effect. It showed how actual progress differed from planned progress over time and allowed each event to be tested against contemporaneous records.
The Court endorsed that approach. It said the referees were entitled to rely on it as a logical and transparent way to demonstrate causation between the breaches and the resulting delay.
Lesson: structured methods that reflect real progress are persuasive. A clear step by step approach that can be verified by records will always be more credible than theoretical counterfactuals.
The value of professional guidance
One side complained that the referees had favoured the other expert because they had followed the Society of Construction Law Delay and Disruption Protocol. They argued that the Protocol is not part of the contract and that ignoring it is not an error of law.
The Court agreed that the Protocol is not mandatory but said it provides useful guidance for good analytical practice when applied with commonsense. The referees were right to treat its principles as relevant.
Lesson: the Protocol is not law, but it represents the collective view of how delay analysis should be carried out. Experts who use its logic show awareness of industry standards. Those who ignore it entirely risk appearing out of step with accepted professional practice.
Proving causation with evidence not speculation
The referees held that the claimant had proved causation by showing how the breaches led to delay. The other party failed to prove any alternative causes. The Court confirmed that the referees were entitled to reach that conclusion.
Lesson: delay analysis is not a debate about possibilities. It is an exercise in evidence. The expert must connect each delay event to what actually occurred on site, using logic, data, and clear reasoning.
What this means for delay experts
This case shows that delay analysis is not just a technical exercise. It is a test of professional judgment. Courts want to see an expert who can explain not only what the programme says but why it matters.
A credible delay expert must:
use a clear and transparent analytical method
explain how cause and effect are linked
test every assumption against real project records
apply recognised guidance with professional sense
avoid speculation that cannot be supported by data
In short, an expert must combine forensic skill with construction insight.
Lessons for solicitors and clients
For those instructing experts, the message is simple. Choose a delay expert who can think as well as analyse. The most persuasive expert is one who can explain the sequence of events in a way that aligns with both the data and the lived reality of the project.
Appointing the wrong expert — one who relies on abstract logic, untested assumptions, or a purely theoretical model — risks having their evidence dismissed entirely.
Final Reflection
Santos v Fluor is a timely reminder that critical path analysis is not about software outputs or diagrams. It is about reasoning, evidence, and professional judgment.
Credible delay experts do not just show where the critical path lies, they show why it moved.
That is what the Court trusted, and that is what every delay expert and instructing solicitor should take from this case.
At Accura Consulting, our team of experts work with clients to create a tailored solution to problems. If you have an issue and want expert support, get in touch.
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