Certification of Skilled Persons under the 2019 Rules: Technical Pleadings and “Conspicuity” Evidence Do Not Justify a Second Liability Expert Without Prior Inquiry

Introduction

This commentary examines the opinion of Lady Poole in Carol Grant and Others v Lothian Buses Ltd [2025] CSOH 98, an Outer House decision on certification of skilled persons under the Act of Sederunt (Taxation of Judicial Expenses Rules) 2019. The tragic background was a fatal road traffic collision in which a bus struck pedestrian Andrew Grant. The substantive damages claim settled, leaving a discrete costs issue: could the pursuers recover, as judicial expenses, fees for a fourth skilled person, Professor Graham Edgar (psychology and applied neuroscience), instructed on perception and visibility (“conspicuity”)?

It was agreed that three skilled witnesses for the pursuers were certifiable: a road traffic investigator (Mr Frazer Davey) and two medical consultants (Professor Richard Lyon and Dr Neil Hunter). The defender opposed certification of Professor Edgar. At the pursuers’ request, the court gave reasons for refusing certification. The case therefore provides practical guidance on when, in personal injury litigation—especially straightforward road traffic accidents—it is reasonable and proportionate to instruct additional skilled persons, and how the timing and diligence of instruction affect certification.

Key issues included:

How the reasonableness and proportionality test in rule 5.3(2)(b) of the 2019 Rules is applied, including the temporal focus “at the time of instruction”.
Whether “technical” pleadings (using terms like “luminance contrast” and “conspicuity”) can by themselves justify specialist perception evidence.
The significance of existing evidence (CCTV, police materials, witness accounts) and an already-instructed road traffic investigator.
What pre-instruction inquiries practitioners should make, including engagement with the opponent to understand the basis of technical averments.

Summary of the Judgment

Applying rule 4.5 and rule 5.3(2) of the 2019 Rules, the court refused certification of Professor Graham Edgar. While it was accepted that he is a “skilled person” (rule 5.3(2)(a)), the pursuers failed to show that instructing him was “reasonable and proportionate” (rule 5.3(2)(b)) in the circumstances of this case.

Lady Poole identified four main factors:

Subject matter: The case was a relatively straightforward road traffic accident. Consistent with Kennedy v Cordia (Services) LLP and Cameron v Swan, the judge could determine visibility and lookout issues without specialist perception evidence.
Evidence otherwise available: There was CCTV, a police collision investigation, witness evidence (including admissible hearsay), and—critically—an already-instructed collision expert, Mr Davey, whose report and photographs covered the physical scene and visibility-related observations.
Issues for determination: The liability questions (adequacy of the driver’s lookout, pedestrian visibility in the dark, speed reduction) were within ordinary judicial experience. The defender’s use of terms like “luminance contrast” did not convert simple issues into complex matters needing an applied neuroscientist.
Steps before instruction: The pursuers retained Professor Edgar before making inquiries of the defenders about the basis and expertise underpinning their technical averments. Upon inquiry (19 June 2025), the defenders identified their own collision investigator (Mr Peter Monteith). Proceeding to instruct a full Edgar report (26 June) was not reasonable or proportionate in light of that information.

Outcome: Certification of Professor Edgar was refused. His charges are therefore irrecoverable as judicial expenses against the defender.

Analysis

Precedents Cited and Their Influence

Rule 4.5 and rule 5.3 of the 2019 Rules: These provisions require court certification before a party can recover charges for skilled persons. Certification depends on (a) the person being “skilled” and (b) the instruction being “reasonable and proportionate.” The court underscored the policy of judicial cost control to protect access to justice.
Philip v Scottish Ministers [2021] CSOH 52 and Webster v MacLeod 2018 SAC (Civ) 16: These authorities anchor the temporal focus of the certification test. The court primarily assesses reasonableness and proportionality at the time of instruction, not with hindsight.
Allison v Orr 2004 SC 453: Settlement after instruction does not retroactively validate or invalidate certification; later events are not generally relevant to the court’s assessment.
Liddell v Middleton [1996] PIQR p36, p42: Often-cited in traffic cases, Liddell cautions against unnecessary expert proliferation and identifies where traffic experts can legitimately assist (e.g., reconstruction from circumstantial physical evidence). This supported certification of Mr Davey but not a second liability expert.
Kennedy v Cordia (Services) LLP [2016] UKSC 6; 2016 SC (UKSC) 59: The leading case on admissibility and the necessity of skilled evidence. If matters are within ordinary judicial knowledge and experience, expert evidence is generally unnecessary and may be inadmissible. This case underpins the judgment’s linkage of admissibility and certification.
Cameron v Swan [2021] CSIH 30: Of particular significance. The Inner House disapproved reliance on generalized “conspicuity” evidence from Professor Edgar in a vehicle-pedestrian collision. Visibility assessments were held to be within the judge’s competence on the facts. Lady Poole relied heavily on this to conclude that perception-specialist evidence was not necessary or proportionate here.
Taylor v Raspin [2022] EWCA Civ 1613 (England & Wales): Persuasive support echoing the principle that courts often can and should determine straightforward visibility and lookout issues without expert assistance.
Stewart v Glaze [2009] EWHC 704 (QB): Explains how, where direct evidence is limited, accident reconstruction expertise can help. This justification supported Mr Davey’s role but did not extend to adding a perception specialist on the same liability axis.

Legal Reasoning

The court’s reasoning layers the rule 5.3 test with admissibility principles and practical litigation conduct.

Temporal focus: time of instruction. Consistent with Philip and Webster, the court assessed whether it was reasonable and proportionate to instruct Professor Edgar when he was retained (initially 30 April 2025; full instruction 26 June 2025). Later settlement or subsequent procedural developments were not decisive.
Necessity and admissibility as gateways. Following Kennedy v Cordia, if the issue is within ordinary judicial competence, expert evidence is unnecessary and may be inadmissible. In a straightforward RTA with CCTV, police investigation, and a collision expert, the judge could assess whether the bus driver should have seen the pedestrian and braked. Because much of the proposed perception evidence risked being inadmissible or of marginal utility, its instruction failed the proportionality test.
Duplication of liability experts is disfavoured. The pursuers already had a qualified collision investigator (Davey) covering the physical and visibility context. Bringing in a second liability expert from a different discipline (psychology/applied neuroscience) to speak to general visibility/conspicuity was disproportionate, especially given Cameron v Swan’s caution about such evidence.
“Technical” pleadings do not transform simple issues into complex ones. The defender’s use of terms like “luminance contrast” and “not conspicuous” did not elevate the case’s complexity. The “mere language” of adjustments cannot justify additional experts if the underlying question is simple: should the driver, using ordinary care, have perceived the pedestrian in time to avoid a collision?
Pre-instruction diligence and opponent engagement. A notable feature of the judgment is its scrutiny of the pursuers’ steps before instruction. The court expected reasonable inquiries to the defender about the basis of the technical averments and the expertise relied upon. When the pursuers finally asked (19 June 2025), the defender identified its road traffic investigator (Monteith). Proceeding to full instruction on 26 June 2025—knowing the defender’s technical case rested on a conventional collision expert—was not reasonable or proportionate.
Access-to-justice policy. The court reiterated that certification rules are a tool for cost control. Unnecessary expert instruction inflates litigation costs and can impede access to justice. This policy lens reinforces strict application of reasonableness and proportionality.

What Is New or Clarified?

The decision concretely applies Cameron v Swan to certification, not just admissibility, signalling that general “conspicuity” or human-perception evidence will rarely be a reasonable or proportionate expense in straightforward pedestrian-vehicle cases with ordinary evidential materials.
The court articulates an expectation of pre-instruction opponent inquiry: before adding a new discipline or a second liability expert, parties should seek clarity on the other side’s technical basis and expertise. Failure to do so may undermine certification.
It emphasises that terminology in pleadings is not determinative of complexity. Practitioners should focus on the real issues for determination and whether those issues truly require skilled assistance beyond what the court and an existing collision expert can supply.

Impact and Practical Significance

The decision will likely influence cost recovery strategies and expert instruction practices in Scottish personal injury and road traffic litigation:

Reduced appetite for “conspicuity”/perception experts in RTAs: In cases with CCTV, police reports, and a collision investigator, courts may view human perception evidence as unnecessary. Practitioners should consider whether such material will be inadmissible or of marginal utility.
Pre-instruction diligence is essential: Before instructing extra experts on liability, parties should:
- Engage the opponent to ascertain the basis and discipline of their technical averments and experts.
- Assess whether existing evidence (including their own collision expert) suffices for the issues to be tried.
- Document the necessity and proportionality rationale at the time of instruction.
Avoid duplicate disciplines on liability: Instructing a second liability expert risks refusal of certification unless there is a demonstrable gap that cannot reasonably be filled by the existing expert and the court’s own assessment.
Pleadings strategy: Using technical language does not compel the other side to respond with new disciplines. Courts will look through labels to substance. Over-technical pleadings may backfire if they trigger unnecessary expense.
Budgeting and costs risk: Parties must anticipate certification risk early. If additional skilled evidence is likely irrecoverable, parties should weigh whether it is still necessary for the case on its merits.
Exceptions remain: The decision acknowledges scenarios where specialist input may be proportionate: cases with sparse direct evidence, unusual optical/lighting phenomena, complex vehicle dynamics, or where an opponent unreasonably withholds material information. But those features were absent here.

Complex Concepts Simplified

Certification of skilled persons: A court’s formal approval that a party was reasonable and proportionate in using a skilled person (expert). Without certification, the other side need not pay that expert’s fees as part of judicial expenses.
Reasonable and proportionate: A practical cost-control test. The court asks whether, at the time of instruction, it made sense to incur the expense in light of the issues, available evidence, and alternatives.
Admissibility vs necessity: Expert evidence is permitted only if it will help the court on matters beyond ordinary experience. If a judge can decide an issue using common sense and the available factual materials, expert input is often unnecessary.
Conspicuity/luminance contrast: Technical terms relating to how visible an object is against its background, particularly in low light. In many traffic cases, judges can decide visibility and lookout without needing a perception specialist.
Collision investigator: A skilled person (often with police background) who analyses physical evidence (CCTV, damage, road marks, lighting) to reconstruct what likely happened.
Executor-dative: In Scots law, a court-appointed executor to administer the estate where there is no will or no executor nominated, here acting in the deceased’s interest.
Admissible hearsay: A statement by someone not giving evidence in court that is allowed into evidence by statute or rule (e.g., what the driver said post-accident).

Practical Guidance for Litigators

Before instructing an additional liability expert:
- Identify precisely which issue requires skilled input and why a judge cannot decide it unaided.
- Audit existing evidence (CCTV, police reports, witness statements, photographs, measurements) and assess whether it suffices.
- Leverage your existing collision expert; ask whether the perceived gap truly sits outside their expertise.
- Engage the opponent early to ascertain the basis of any technical averments and the discipline of their expert(s).
- Record the justification at the time of instruction; anticipate later certification scrutiny.
On pleadings: Avoid over-technical language unless genuinely necessary. If encountering such language, do not assume you must mirror it with a new discipline. Seek clarification first.
Link necessity to admissibility: If evidence would likely be ruled inadmissible or unnecessary under Kennedy v Cordia, think twice about instructing; certification will be at risk.
Timing matters: The court will primarily assess reasonableness at the time you instructed the expert. Later settlement or disclosure does not rescue an earlier disproportionate choice.
Recognised exceptions: Consider specialist perception or other niche experts only where there are unusual optical/lighting conditions, complex psychophysical issues, or sparse direct evidence that cannot be resolved by a collision expert and the court’s own fact-finding.

Conclusion

Lady Poole’s decision in Carol Grant and Others v Lothian Buses Ltd reaffirms and sharpens the certification standards under the 2019 Rules. The court refused certification of a perception expert in a straightforward pedestrian-vehicle collision because:

The issues of visibility and lookout were within ordinary judicial experience.
There was already substantial evidence (CCTV, police investigation, witness accounts) and a certified collision investigator’s report.
Technical wording in pleadings does not make simple issues complex.
The pursuers did not make timely inquiries of the defenders about the basis of the technical averments before instructing a new discipline.

The judgment underscores that certification is not a box-ticking exercise but a substantive, context-sensitive control on litigation costs designed to protect access to justice. It aligns certification with admissibility principles from Kennedy v Cordia and applies the Inner House guidance in Cameron v Swan to the recurring phenomenon of “conspicuity” evidence in RTA cases. The practical message is clear: do not duplicate liability experts, do not be driven by technical vocabulary alone, and do undertake diligent, early engagement with your opponent before incurring specialist expense. Where the court can safely decide using common sense, the evidence already to hand, and a single collision expert, additional expert layers will likely be deemed disproportionate and uncertifiable.