Proving Disruption - What the Courts Now Accept

The Queensland Supreme Court decision in Santos Limited v Fluor Australia Pty Ltd [2025] QSC 184 provides one of the clearest explanations yet of what disruption means, how it must be analysed, and what level of proof the courts expect from experts and parties.

The case involved competing arguments over productivity and cost inefficiency on a large-scale project. The Court’s reasoning now sets a practical standard for disruption analysis in Australia.

Disruption is about inefficiency, not time

At paragraph [217], Justice Flanagan explained:

“Disruption claims often occur where there is a disturbance of the contractor’s regular and economic progress and or delay to a non-critical activity even though, on occasion, there is no delay or only a small delay in completion.”

The nature of the claim

At [250], the Court made clear:

“The case brought by Santos is not one for the cost of acceleration. It is a disruption claim for the cost of work done inefficiently. The costs include those paid to workers and supervisors to get the work finished on time.”

What a disruption analysis must demonstrate

The respondent argued that a proper disruption analysis required a detailed comparison between planned and actual productivity. At [198], the Court recorded that:

“To properly assess the additional costs that could be causally linked to the alleged disruption would require undertaking a series of complex analyses to identify what changes from the planned (or required but for the alleged disruption) versus the actual occurred to the drivers of cost, including work fronts, crew count, work shifts, headcount, man-months, crew size and duration of work.”

This view represents the traditional expectation of a measured mile or productivity comparison study. The Court accepted that such an approach may be appropriate in some cases but emphasised that what matters is not complexity but proof of causation.

What the Court actually accepted

At [225], the referees’ findings adopted by the Court stated:

“Fluor increased its workforce to complete the wellpads on time. The need was brought about by the earlier disruption to the wellpad work. The increase in manpower was accompanied by an increase in the costs of supervisors and foremen… All categories of costs were incurred as a consequence of the need to increase the workforce.” 

This was a factual disruption analysis, not a modelled one. The referees relied on evidence of manpower ramp-up, cost records, and project history to demonstrate that the inefficiency and associated costs were caused by disruption events.

The Court accepted this reasoning. It confirmed that a disruption analysis based on factual cause and effect can satisfy the legal test where the evidence clearly links breach, disturbance, inefficiency and cost.

Causation must be proven, not assumed

The Court then reaffirmed the key legal principle at [3094]:

“Although there is a widespread assumption that, when work is speeded up, it will lead to increased cost, whether that is so is not a matter of assumption; it is a matter of fact, which is to be proved in each particular case.”

This quote should be at the top of every quantum expert’s mind. It defines the boundary between opinion and proof. Courts will not accept assumptions about inefficiency. The cause and consequence must be proven with evidence.

Methodology and the SCL Protocol

While the delay analysis in the case used the as-planned versus as-built in windows method from the Society of Construction Law Delay and Disruption Protocol (2nd Edition, 2017), the same analytical philosophy underpins disruption work.

At [561], the Court noted: 

“Certain methods start with identifying an event (the cause) and then seeking to establish the impact of that event (the effect). Other methods first identify critical delay (the effect) and then seek to establish the event that caused that delay (the cause).” 

For disruption, this cause and effect reasoning is equally relevant. The key is to show that the disturbance had a demonstrable and traceable effect on the efficiency of work.

The standard now set by the Court

The decision clarifies what Australian courts expect in disruption matters:

• Disruption concerns inefficiency, not delay | [217]

• Disruption is not acceleration | [250]

• Complex modelling is not mandatory | [198], [225]

• Factual evidence of cause and effect can suffice | [225]

• Causation must be proven as fact | [3094]

• Courts look for logical and contemporaneous linkage | [225], [561]

Practical lessons for experts and practitioners

1. Prove the cause and effect. Link the event, the disturbance and the inefficiency through contemporaneous evidence.

2. Focus on facts, not formulae. Cost records, supervision logs and resource curves carry more weight than theoretical models.

3. Avoid assumption. Do not infer inefficiency from correlation or labour peaks.

4. Separate disruption from delay. The claim is about efficiency, not time.

5. Keep it clear and reasoned. The best expert evidence tells a logical story supported by documents.

Conclusion

The Court in Santos v Fluor [2025] QSC 184 accepted a disruption analysis based on factual cause and effect rather than complex productivity modelling. It reaffirmed that disruption must be proven by evidence, not assumption.

The message is clear: courts will accept disruption analysis that is logical, evidence-based and causally sound. Complexity is no substitute for proof.

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