Reid v MCM Building & Civil Engineering Construction Ltd: Apportionment in Mesothelioma by “Fibre/ml-Years” Where Exposure Intensity Differs

1. Introduction

John Reid sued two former employers—MCM Building & Civil Engineering Construction Limited (first defender) and Pyramid Joinery & Construction Limited (second defender)—in the Scottish Court of Session (Outer House) after being diagnosed in 2024 with pleural mesothelioma.

The action proceeded as a proof before answer limited to liability. Key matters were significantly narrowed by joint minute: mesothelioma was admitted; the defenders accepted that at the material times they knew or ought to have known asbestos exposure was dangerous; and (critically) causation was conceded in the sense that if the pursuer proved exposure with a defender, that exposure would be treated as a material increase in risk.

Accordingly, the proof focussed on two issues:

  1. whether the pursuer was exposed to asbestos in each employment; and
  2. if so, how liability should be apportioned as between the defenders (contribution).

2. Summary of the Judgment

Lord Harrower held that the pursuer was negligently exposed to asbestos during both employments and that both exposures materially increased the risk of developing mesothelioma. Applying the Fairchild exception and section 3(2) of the Compensation Act 2006, both defenders were found jointly and severally liable for the whole loss.

For inter se contribution, the court rejected a purely “relative duration of exposure” approach under section 3(4) of the Compensation Act 2006 as inappropriate on the facts (because intensity and nature of exposure differed materially), and instead used a “broad axe” assessment based on estimated cumulative lifetime exposure (expressed as fibres/ml-years). Apportionment was fixed at:

  • 0.092% to the first defender; and
  • 99.908% to the second defender.

The court also refused the first defender’s motion to lodge late productions under RCS 43.8, holding it came too late and would prejudice other parties.

3. Analysis

3.1 Precedents Cited (and Their Influence)

(A) Proof, witness handling, and reliability of testimony

  • McKenzie v McKenzie 1943 SC 108
    The first defender invoked this authority to attack the pursuer’s evidence, arguing that leading questions (and use of a sworn affidavit) undermined its reliability. Lord Harrower distinguished McKenzie: there the evidence was reduced to monosyllabic answers to extracts from precognitions; here, the affidavit was adopted without objection and the pursuer was meaningfully cross-examined by experienced counsel. The court treated McKenzie as a warning on weight, not a bar to the evidence being used.
  • Kerr v HM Advocate 1958 JC 14, HM Advocate v McSween, 2007 SLT 645, and Beurskens v HM Advocate [2014] HCJAC 99; 2015 JC 91
    These criminal authorities were deployed to explain why precognitions may be regarded as “filtered through the mind of another” and thus treated with caution. Lord Harrower used them by analogy to reinforce a key distinction: a sworn affidavit of the witness (especially where unchallenged as to admissibility) is not automatically vulnerable to the “filtered” objection that often attends precognitions.
  • Gilluley v Greater Glasgow Health Board 1987 SCLR 431 (Sh Ct) and Walker and Walker, The Law of Evidence in Scotland, 5thEdition (2020), at paragraph 5.13.1
    Cited in the first defender’s broader challenge to the pursuer’s credibility and the dangers of leading evidence on central disputed facts. The court’s approach shows these concerns remain live, but their practical bite depends on the totality: adoption without objection and robust cross-examination mattered.
  • Gestmin SGPS SA v Credit Suisse (UK) Ltd [2013] EWHC 3560 (Comm); [2020] 1 CLC 428 and Henderson v Benarty Medical Practice [2022] CSOH 28
    The second defender relied on Gestmin to emphasise the frailty of memory and reconstruction in litigation. Lord Harrower accepted the psychological insight but confined its “documentary preference” guidance to its commercial context (where documents should exist). In asbestos cases often lacking contemporaneous documentation, the court must still evaluate oral testimony, with cross-examination assisting the assessment of a witness’s working practices and plausibility.
  • Prescott v The University of St Andrews [2016] CSOH 3 and Bannister v Freemans plc [2020] EWHC 1256 (QB)
    Used as comparators in asbestos litigation where the court was not persuaded about exposure narratives (e.g., professionals/office workers; confusion between dusty activities). Lord Harrower distinguished those fact patterns from a labourer’s close proximity to (and handling of) the very materials alleged to contain asbestos.

(B) Causation in mesothelioma: material increase in risk

  • Fairchild v Glenhaven Funeral Services Ltd (t/a GH Dovener & Son) 2003 1 AC 32
    The foundation for the “Fairchild exception” to the “but for” test in mesothelioma: where multiple exposures could have caused the disease and it is impossible to identify the causative fibre, liability may be established by showing a defender’s breach materially increased the risk. Lord Harrower applied this framework to impose joint and several liability once exposure/negligence was proved.
  • Sienkiewicz v Greif (UK) Ltd [2011] UKSC 10, [2011] 2 AC 229
    Reinforces that even where only one tortfeasor is sued, risk-based causation principles remain central in mesothelioma. Its presence underlined that causation is approached through risk contribution rather than proof of the “causative fibre”.

(C) Apportionment / contribution and the “broad axe”

  • CAR v Eljamel and NHS Tayside [2021] CSOH 130 (upheld on appeal [2022] CSIH 34; 2022 SLT 881)
    The second defender cited this for the proposition that nil apportionment is competent. Lord Harrower accepted competence in principle, but distinguished it: in CAR the second defenders’ negligence caused no significant harm; in mesothelioma, where (on the court’s findings) both exposures materially increased risk, nil apportionment was treated as inappropriate.
  • Grier v Lord Advocate 2023 SC 116
    Cited for the “conventional broad axe with a blunt blade” approach to difficult quantification. The court used this as the methodological anchor for making necessarily rough evaluative judgments about dose, duration and intensity decades after the events.

(D) Contextual authorities mentioned but not engaged on merits

  • Kerr v Midlothian Council [2024] CSOH 112 and Bannister v Freemans plc [2020] EWHC 1256 (QB)
    Not decided here, but noted as cases where courts wrestled with whether low occupational exposure is “material”. This dispute evaporated in Reid because defenders conceded materiality once exposure was proved.

3.2 Legal Reasoning

(A) Case management and fairness: refusal of late productions

The first defender sought to lodge an occupational hygiene report and other materials late under RCS 43.8. The court refused, emphasising lateness and prejudice. The ruling also prevented a late pivot toward a de minimis-type argument (suspected from tendering the Hodgson & Darnton article), particularly where that line was not foreshadowed on record and would have altered the case’s forensic balance.

(B) Affidavit evidence, leading questions, and weight

Lord Harrower treated the affidavit as part of evidence in chief because it was adopted without objection. The court rejected the idea that use of the affidavit and some leading questions rendered the evidence “worthless” (as in McKenzie v McKenzie 1943 SC 108), stressing (i) the affidavit’s status as sworn testimony rather than a “filtered” precognition, and (ii) the corrective function of full cross-examination.

(C) Proving exposure in the absence of documents

The decisive factual question was whether the materials involved were asbestos-containing:

  • First defender exposure: the pursuer’s account of removing corrugated asbestos roofing from garages was supported by occupational hygiene evidence identifying such roofing as typically asbestos cement.
  • Second defender exposure: although the managing director suggested local authority surveys/tendering would have identified asbestos and specialist contractors would have been used, the court preferred the pursuer and (especially) Peter Wright on repeated handling/bagging of asbestos debris, the existence/use of locked asbestos skips, and the fireproofing function suggesting AIB. The court expressly held any assumption of regularity was rebutted by the evidence.

The court also highlighted that Gestmin should not become a blunt reason to discount oral testimony in contexts (like historical asbestos exposure) where documents are commonly absent. Here, the court found the pursuer’s working-practice evidence coherent and corroborated.

(D) Causation and liability

With exposure proved, the legal route to liability was straightforward because the defenders had conceded that exposure would satisfy a material increase in risk. The court explicitly applied Fairchild v Glenhaven Funeral Services Ltd (t/a GH Dovener & Son) 2003 1 AC 32 and section 3(2) of the Compensation Act 2006, finding the conditions in section 3(1) fulfilled, and imposing joint and several liability.

(E) Apportionment: why section 3(4) “relative duration” was displaced

The legally important move is the court’s explanation for disapplying the default approach in section 3(4) of the Compensation Act 2006 (relative lengths of exposure). Lord Harrower considered that approach inappropriate because:

  1. it implicitly assumes comparable exposure intensity across employments, contrary to the evidence (asbestos cement removal versus rough-handled AIB debris); and
  2. even “duration” required rough estimation, so it did not avoid broad-axe evaluative judgment.

Instead, the court used estimated cumulative dose proxies (fibres/ml-hours converted to fibres/ml-years), making findings on: (i) time exposed, (ii) average concentration, and (iii) (to an extent) asbestos type (chrysotile versus amosite). The judgment is candid that this is still a broad-axe exercise; it is presented as more appropriate than time-only apportionment because it better reflects differences in intensity and material.

(F) Rejecting “nil” apportionment on these facts

The court rejected the second defender’s “nil contribution” submission. While acknowledging nil is competent (per CAR v Eljamel and NHS Tayside [2021] CSOH 130), Lord Harrower held it would be wrong where the court has found both defenders’ negligence materially increased risk and thus both contributed to the loss in the relevant legal sense. This protects the internal logic of mesothelioma risk-causation: if exposure satisfies the causation test against a defender, it normally cannot be treated as contributing “nothing” for contribution purposes absent some exceptional finding (e.g., no significant harm attributable, as in CAR).

3.3 Impact

  • Apportionment methodology in Scottish mesothelioma litigation: The judgment provides a clear example of the court using dose/intensity-informed apportionment (fibres/ml-years) as “more appropriate” than section 3(4)’s time-based default, where the evidence supports substantial differences in concentration and material. Future contribution disputes can be expected to focus more heavily on occupational hygiene modelling, task-based concentrations, and reasoned “broad axe” findings.
  • Constraining “regularity” assumptions: Arguments implying that public-sector procurement/surveys would necessarily prevent asbestos exposure were treated as rebuttable and rebutted on evidence. This may encourage defenders to lead concrete site-specific documentation if they wish to rely on systems-based improbability arguments.
  • Affidavits in civil proofs: The court’s treatment reinforces a practical point—if a party wishes to challenge the use of an affidavit adopted as evidence in chief, it should object at the point of adoption. Absent objection, the dispute typically shifts to weight, tested by cross-examination.
  • “Nil contribution” is exceptional in risk-causation cases: While competent, nil apportionment is unlikely where the court has positively found exposure and material risk contribution against both parties.

4. Complex Concepts Simplified

Mesothelioma and the “Fairchild exception”
Mesothelioma can be caused by inhaling asbestos fibres, but science cannot typically identify which specific fibre (or which exposure episode) caused a particular person’s cancer. The “Fairchild exception” allows causation to be proved by showing the defender’s breach materially increased the risk, even if “but for this exposure the disease would not have happened” cannot be proved in the ordinary way.
Joint and several liability
If multiple defenders are liable, the pursuer may recover the full loss from any one of them (subject to other rules not in issue here). The defenders then argue among themselves about fair sharing (contribution).
Contribution and apportionment
“Contribution” is the mechanism by which liable defenders re-allocate the financial burden between themselves. Here it was pursued under section 3 of the Law Reform (Miscellaneous Provisions) (Scotland) Act 1940, preserved in mesothelioma by section 3(3) of the Compensation Act 2006.
Section 3(4) of the Compensation Act 2006 (default rule)
The statute says the court should have regard to relative lengths of exposure, unless the parties agree otherwise or the court considers another basis more appropriate. Reid is an instance where the court found “another basis” more appropriate due to differing intensity/type of exposure.
“Fibres/ml-years” (dose proxy)
A modelling tool: estimated average airborne concentration (fibres per millilitre) multiplied by time exposed, then expressed over a year unit. It is not a precise measurement in historical cases; it is a structured approximation used to inform a “broad axe” apportionment.
The “broad axe”
A judicial recognition that some quantifications cannot be done precisely, especially long after events. The court still must decide, using reasonable assumptions and the evidence available, rather than refusing to decide.

5. Conclusion

John Reid against MCM Building & Civil Engineering Construction LTD and another illustrates how Scottish courts will pragmatically decide historical asbestos disputes: they will accept the limits of memory without abandoning oral evidence where documents are absent; they will apply the Fairchild/Compensation Act risk-causation framework once exposure is proved; and, crucially, they may depart from section 3(4)’s time-based default for contribution where it would obscure stark differences in exposure intensity and material.

The practical significance lies in the apportionment holding: the court treated “relative duration” as an imperfect proxy and preferred an exposure-intensity-informed approach, expressed as fibres/ml-years, while candidly acknowledging this remains a broad-axe exercise. For future mesothelioma contribution claims, the judgment signals that occupational hygiene evidence and reasoned exposure modelling can be decisive in achieving a “just” allocation between liable employers.