Behaviour change

Learning from: expert witnesses

Three specialists outline five key lessons that OSH professionals can consider in their work.

Illustration: Gary Neill

When someone falls from 20 m, it doesn’t need calculations of the effect of gravity on a mass over a distance to work out that the risk of severe injury was foreseeable. Some hazards are comprehensible to the public, or the hypothetical “man on the Clapham omnibus”.

Similarly, if the working platform at 20 m had no guarding and no other means of preventing a fall were provided, the same man or woman on the 21st century electric bus can see that there were reasonably practicable measures that could have been taken to prevent the incident.

However, even occupational safety and health specialists have struggled to understand the arguments in a case such as that brought by viola player Christopher Goldscheider against the Royal Opera House in London. Our conventional understanding of noise-induced hearing loss (NIHL) is challenged by the discussion of acoustic shock and the relationship between directional noise and frequency of sounds. It would take an expert to work it out.

Dr Chris Nelson, MIOA, Finch Consulting

Nelson’s first degree was in physics with musical acoustics, and he completed a doctorate with the Institute of Sound and Vibration Research (ISVR) at the University of Southampton on vibration-induced white finger in dockyard employees.

After a spell with the Institute of Naval Medicine he moved to the HSE as a specialist inspector for noise and vibration, developing policy, guidance and regulation. He now works as a principal consultant at Finch Consulting providing employers with advice on reducing the risk of noise-induced hearing loss and vibration injuries (both hand-arm vibration syndrome, HAVS, and damage associated with whole-body vibration). He also prepares expert evidence, most of which relates to civil claims for noise- or vibration-related personal injuries. Nelson has been instructed on behalf of defendants in HSE prosecutions for HAVS.

Nelson currently chairs the BSI standards committee Chris-Nelsonon human responses to vibration. He is a member of the Institute of Acoustics and is listed in the UK Register of Expert Witnesses.

How people become expert witnesses varies. Some start with an academic approach, some with a more hands-on background, but all achieve a high profile in their profession, marked by professional membership and academic achievement. 

IOSH Magazine asked three expert witnesses – Dr Chris Nelson, a principal consultant at Finch Consulting; Dr Mike Webster, founder of MPW R&R, which specialises in consulting, forensic and expert witness services; and Professor Richard Booth, of safety consultancy Hastam – about their work (see individual panels).

As well as providing their expertise to unpick the technical challenges in safety and health cases, both civil and criminal, they have lessons to feed back to OSH practitioners. They offer five principal lessons that can benefit the work of professionals:

  • Stay impartial
  • Know your limits
  • Don’t sugar the pill
  • Create an evidence narrative
  • Write for the future

Stay impartial

The IOSH code of conduct explains that any OSH practitioner acting as an expert witness must remember that their “overriding duty will be to the court rather than to any person instructing you or with an interest in the outcome of the proceedings”.

Nelson has a strict interpretation of this. “As an expert witness I am not trying to prove the case in one direction or the other. My responsibility is to the court. I produce the same opinion, whoever is instructing.” To test his own impartiality, Nelson asks himself a simple question when he has finished a report: “If I’d been instructed by the other side, what would I change? If the answer is nothing, that’s fine. If I think I’d have written something differently, I’d double check the evidence I was making that judgement on.”

This impartiality is reinforced by the approach taken by courts on many noise and vibration issues. Instead of pitting experts from each side, often a single joint expert is appointed, with one report available to both sides. Webster and Booth, by contrast, are usually instructed by one side or the other. Webster still agrees with the principle of impartiality: “I look at what the law requires in a given situation and then assess what the organisation has said it would do and what it actually did. I determine if the differences are significant and whether any lapses below the standard required contributed to the accident or incident.”

Booth agrees that “the first duty of an expert witness is to the court” but adds: “Inevitably there will be differences between the report produced when instructed by the prosecution’s or complainant’s solicitors than when instructed by the defendant. If I’m instructed by the defence, it is not my duty to do the prosecution expert’s job for them.”

Mike Webster, CEng, FICE, FIStructE, founder MPW R&R

Webster’s first degree in civil engineering was studied part-time while working for the Cement and Concrete Association. He completed his MSc in concrete structures when he worked for the engineering consultancy Mouchel on the design, appraisal, repair and site supervision of new and existing building and bridge structures. He moved to the British Cement Association to produce guidance for the assessment of safety of concrete structures, completing a PhD in the assessment of corrosion-damaged concrete structures.

He returned to consultancy and led independent reviews of CDM 1994 and CDM 2007, and of the use of CDM 2007 in the construction of the London 2012 Olympics.

Webster set up MPW R&R in 2014 to provide consulting, forensic engineering and expert witness services in construction and structural safety and the application of the CDM and other safety regulations.

He has been an expert witness in cases involving corporate manslaughter, gross negligence Mike-Webstermanslaughter and breaches of the Health and Safety at Work Act and the CDM Regulations.

He is conscious of how easily an expert witness can fall into hindsight and confirmation bias when producing a report. “I’ve seen it in prosecution reports when I’ve been on the defending side,” he says.

“I’m not blind to the fact that I might be guilty of it myself. Hence in every report I include a paragraph explaining what it is and how all expert reports ought to be reviewed with it in mind.”

Even for OSH professionals with no intention to be an expert witness, a reminder to be impartial and to watch for bias is useful (see “Clear your head”, IOSH Magazine, February 2018). The next time you do a risk assessment, ask yourself: “Am I hoping to find that everything is ok?” If you are writing an accident report, are you being steered towards placing the blame in a particular direction? For example, if your audience is the board, consider Nelson’s question and ask yourself, “Would I have produced a different report if my customer was a trade union, staff representative or the family of an injured party?”

Know your limits

The IOSH code of practice reminds us that all members should “ensure they are competent to undertake proposed work” and not carry out an assignment unsupervised which “requires specialist skills or knowledge that are beyond the limits of your competence”. This point is reinforced by our expert witnesses, who all report passing work to more specialist experts when the issue is outside their area of expertise. Finch Consulting and Hastam have other experts in house, and each of the three experts interviewed here have a network of associates and contacts to whom they can refer clients.

However, it is not always obvious at the start what expertise will be important. Nelson says some legal teams ask solely for an “expert engineering report” without understanding what they need. “I have turned down one or two cases that initially appeared to be HAVS claims but turned out to require an ergonomist rather than a vibration expert,” he says.

Booth gives his own example: “One case was expected to turn on the way equipment had been procured and managed, not on the detailed design of the equipment. The expert on the other ‘side’ was a design specialist for the specific equipment, but knew little of construction site safety management. As it turned out, the case turned on the detailed design.”

Don’t sugar the pill

Some expert witnesses find themselves under pressure to steer a report in a particular direction. As Booth explains: “I have been asked by barristers on either side of a case to tone down my remarks. But I need to be able to defend anything I write in court, and I would lose all credibility if I watered down my reports.” He gives an example of the time he advised a client to plead guilty. “They ignored my advice and fought the case. They were found guilty. It would have been better for them to accept the facts of the case earlier.”

Nelson agrees that sometimes clients don’t want to hear what you have to say. “Don’t go native. Don’t avoid delivering the bad news just because fixing it will be expensive or inconvenient.” Rather, he advises: “Be clear what assumptions you have made and where you have sourced your evidence.”

When you write your report, think of your future self – or someone – reading it in two years’ time. Will it be understood by then?


Toning down the message is bad for the client in the long run, as Webster explains: “With the change in sentencing rules in 2017 the scope for a reduction for a guilty plea has been limited to those organisations that plead guilty at the earliest opportunity.” As a result, solicitors ask for expert reports much sooner. “They need to find out early whether the organisation had in fact been doing everything reasonably practicable. Legal teams would rather know the situation from me up front than learn about it later from the other side’s expert.”

Booth echoes this thought: “The main thing I’ve learned from expert witness work is that, before an accident, organisations never think they are doing a bad job. Too often, senior managers have been fooled by auditors – or even their own middle management or in some cases by HSE inspectors – into thinking everything is ok.”

OSH professionals similarly should be prepared to deliver bad news to clients or employers, particularly when it’s still at the stage where something can be done about it.

An aerial photo of the Buncefield fuel depot in Hertfordshire, one year on from the massive explosion. © Ins News/Shutterstock

Create an evidence narrative

Nelson’s explanation of how he investigates provides another lesson for OSH professionals. “I’m looking for a narrative in how an organisation managed a problem,” he says. “A risk assessment or audit shows me a hazard was identified, but it doesn’t always tell me what was done about it.”

Nelson highlights what he sees as a growing trend. “Therehas been a lot of discussion over the past few years about how to measure vibration. But if employers focus their efforts on more and more measurement without putting risk reduction measures in place, all they are doing is providing evidence against their organisation should a claim ever arise.” He refers to this data as “guilty knowledge” and suggests “rather than fretting about precisely how high a risk is, just work to reduce it”.

Webster also points to the importance of being able to show the evidence story in relation to risk assessments, especially when bundled up with method statements (known as RAMS).

“There is a lot of focus on RAMS documents by both prosecution and defence,” he says. “The quality of the RAMS is important, but you also need to be able to show that the contents were communicated to everyone who needed to know and were followed.”

This presents a challenge to OSH professionals. Writing down every interaction with every staff member would be onerous and would result in a cavalcade of paperwork and time spent meeting the demands of data protection legislation.

As Nelson points out, NIHL cases could arise decades later. “Woolly witness statements such as ‘the claimant would have undergone induction training that covered noise’ or ‘hearing protection was available to wear when appropriate’ don’t make a great evidence story,” he says.

Webster recommends keeping records of what is covered in each toolbox talk and induction, along with a signed list of attendees. Retrospectively, do you have evidence that there was a process for providing induction training for all new staff 20 years earlier? Could you show what was covered in that training? If you use e-learning, can your provider tell you what was covered in an older version of a course?

Dr Professor Richard Booth, CEng, FIMechE, CFIOSH, Hastam

Professor Richard Booth started as a mechanical engineering apprentice in the motor industry. In 1972 he gained a PhD in fatigue testing of vehicle components and was appointed a lecturer at Aston University.

Booth’s first experience as an expert witness was in the late 1970s in the US in two civil cases relating to disabling accidents on power presses. He set up Hastam in 1984 with Dr Tony Boyle and Professor Andrew Hale.

He was on the Advisory Committee for Safety in Nuclear Installations Human Factors Study Group, established following the 1986 Chernobyl disaster. He was the HSE’s expert in the prosecution of Corus UK following the 2001 Port Talbot blast furnace explosion, and acted for Total after the 2005 Buncefield explosion.

Alongside consultancy, research and lecturing he works as an expert witness in criminal and civil cases both for defendants and for prosecutors or claimants.

He provides expertise on chemical processing, Richard-Boothmanufacturing, rail and energy industries, as well as advising on culture, safety management systems, and human factors.

Emphasising that “written, contemporary notes provide more certain evidence than recollections”, Webster suggests all managers should “keep a day book in which you write a short note of who said what to whom, with any significant decisions made. Importantly, note the reasons decisions were made.”

If actions are noted they must be tracked and closed out. Booth describes one of his investigations in 2001: “When I investigated the Port Talbot furnace explosion (see Booth’s panel), reading through the shift logs I found numerous failures of water-cooling pumps, the primary cause of the explosion. In the six weeks before the explosion six were noted and not acted on.”

This was not unique, he said, referring to the Buncefield oil storage explosion and fire in Hertfordshire, southern England, in 2005. “The prosecution expert for Buncefield found that supervisors had recorded that tank gauges were unreliable, but the managers knew nothing of it.”

One solution to this is technology. “At both Port Talbot and Buncefield the records were written by hand, often with atrocious handwriting,” Booth says. “The level of detail varied enormously from ten words to many paragraphs. A computer-based system that prompts for information and sends any headlines to the gaffer’s desktop as an alert would be a vast improvement.”

Write for the future

Nelson has another tip on reporting drawn from his experience as an expert witness, but of relevance to any OHS documents with a lifespan of more than a few weeks. “If you are called to explain a report in court, you are not allowed to take any notes with you into the witness box,” he says. “All you have is the report you have written, which you might have completed some months – or even years – before the case comes to court.

“When you write your report, think of your future self – or someone else – reading it in two years’ time. Will it be understood then? You could be asked why you left something out of your report. What was obvious to you when you wrote it might not be when you have to defend it. So, include in the report an explanation of anything left out as well.”

This lesson also applies to risk assessments. If you leave a hazard out of an assessment because you didn’t regard it as significant at the time and later there is an accident relating to the hazard, how do you show you did consider it?

Another learning point could be to imagine that any report, policy or assessment you write was being cross-examined in court. Would it stand up to questioning? Do you have the evidence to back it up? Perhaps ask a “critical friend” to challenge your work – can you defend it?

Webster also warns about the information people write down but would not want appearing as evidence. “Emails do make it to court documentation,” he says. “Don’t say anything to anyone in an email that you wouldn’t feel happy being examined on later in court.”

The role of the expert witness is one that OSH professionals need to be aware of. These five principles help us to understand their thinking, and to direct our own efforts to giving them more evidence in our favour if we ever need their services.



Bridget Leathley is a freelance health and safety consultant, providing risk management support in facilities, retail and office environments.  She delivers face-to-face safety training including IOSH and bespoke courses, and contributes to e-learning courses through evaluations and design work.  She has been writing for health and safety publications since 1996.  

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