Who This Article Is For

You might be forgiven for wondering how a reference to an Agatha Christie murder mystery relates to serving as an expert witness, other than a questionable play on words – however, just as in this ‘who dunnit’ novel, keep reading and I promise all will eventually become clear…

On a more serious note, the primary aim of this article is to help individuals think about whether this line of work might be for them – and for attorneys to help assess if an individual is indeed suited to acting as a legal expert.

My first assignment as an expert witness came through a personal recommendation and introduction by a colleague. Looking back, this experience proved to be a pivotal and career defining moment that led to the opening of many doors.   

Expert witness consultancy is multi‑faceted and often quite different from an expert’s main line of work. At risk of stating the obvious, legal firms normally engage expert witnesses to help inform legal cases, with these typically being focused towards intellectual property and patent disputes, disagreements concerning copyright, quality issues within manufacturing, disputes over contract fulfillment and accusations of medical or other professional negligence.

So, what might the expert or the legal firm expect from each other?

Experiences of Acting as an ‘Expert’

My first expert witness assignment involved me supporting a team of attorneys acting on behalf of a manufacturing company being accused of patent infringement.

It is completely normal for first time ‘experts’ to feel a little nervous and not know quite what to expect; I certainly did.

Many years on from this, my first assignment as a legal expert, I have in turn now recommended a number of colleagues to attorneys, where I could see their expertise aligning with specific cases.

Two questions I am often asked are: ‘How do you become an expert witness’ – and – ‘What is involved with this line of work?’. My normal response to both questions is to share with them my journey – and this is what I will try to do here. I don’t believe any two peoples’ stories will be the same, although there will often be similarities and lessons to be learned. I hope you find my observations and musings helpful!

My own career has followed the path of being a research academic with most of my work being focussed towards fundamental research and then translating this from the lab into fully commercialised products and technology. During this time, I have however, worked closely with the manufacturing sector, with science from my lab also having given rise to the formation of a university spin‑out company.

Other experts of course may come from very different career paths, with expertise coming from example, multi‑national corporations, SMEs or any one of a number of professions.

An individual’s journey does not matter, so much as the ability to advise the attorney on matters of technical or experiential expertise – with an authority that comes from a being a recognised expert in the field. Coupled to this the expert must have the ability to articulate their knowledge and thinking to others in a clear and intelligible manner to, for example, a judge, members of a jury or arbitration panel.

Like many first-time experts, I approached my first case with more than a little trepidation, but agreed to explore with the lead attorney, whether I might be able to help.

The attorney’s office sent me an initial briefing which suggested to me that their client did indeed not only have a prima facia case that needed defending against an accusation of patent infringement by a larger and predatory competitor. This whetted my sense for the need for justice – and an appetite to explore the facts of the case in greater depth. Following the signing of a non-disclosure agreement, I began reading volumes of background documents, which while raising a host of questions – also helped scope in my mind the outline of the two opposing legal arguments.

Note, at this point I was still not at this point formally engaged by the legal firm: As a scientist by my inclination is always to drill into and gather evidence underpinning any case to inform my understanding of all aspects of a potential case. I explained to the attorney at a very early stage, that if I was to act as an expert witness, I needed to assure myself that I was acting to help support a case that I truly believed in myself. While fearing this might lose me the assignment, I later learned that this approach had actually helped secure the confidence of the legal team – and had in fact convinced them I was the person they wished to work with.

This approach remains a personal code of conduct that I still adhere to before accepting any assignment. Apart from the moral aspects, I do believe that it is far easier to argue any case if you truly believe in what you are saying. Mark Twain famously remarked that, ‘you do not have to remember what you said sometime earlier if you only ever speak the truth’, and again in a similar context in Shakespeare’s Hamlet, Polonius, advises his son that while at University to ‘above all unto thine own self be true’.

It is so important to remember that your first role as an expert witness is to serve others – and if integrity shines through, then success is far more likely to follow. If you are not sure that your expertise aligns with a particular case – or you do not believe in the tenant a case, discuss this with your attorney; they will respect you for this – and I suspect be far more likely to come back to you in the future. Conversely of course, if your expertise is found wanting in a case, a legal firm will be far less likely to ask you to work with you in the future.

Early Stages and Preparation of Expert Opinions:

Returning to my own experience – and having decided I would be happy to accept this case, terms and conditions were agreed and the proper work began. The next stages comprised a number of in‑depth and lengthy teleconference in which the lead attorney and I mutually discussed the outline of the relative merits and potential weaknesses of our clients’ position – along with technical aspects to the patents in play.

One point that struck me early on was how closely my approach as a scientist in which all arguments are based on evidence aligns closely with the way in which the legal profession operates. It is important to remember of course that as an expert witness you will not be expected to be an expert in the law; the attorney will advise you on all legal aspects as and when needed. Similarly, the attorney will look to you for technical or scientific or professional practice advice. This is a clear example of where two parties cooperate so that the whole is greater than the sum of the parts.


The next key step for expert witnesses from both the plaintiffs’ and defendants’ teams is to prepare written expert opinions. In practice, these are almost always developed in a two-way back and forth iterative process, in which the expert articulates their views to the attorney, who in turn helps shape these into a legal format. Much of this work can be undertaken using on-line editing tools or teleconferencing.

 It is crucial that both the expert and lawyers continue to develop the opinions until both are in agreement with every nuance. These ‘opinions’ will be referred to – and relied upon as evidence as the case proceeds and this is why they are so important. It is worth stressing each and every word of these opinions matter – and it is crucial that as an expert ‘that you clearly say exactly what you mean – and mean exactly what you say’.  For these reasons, opinions often take some time to prepare – being subject to extensive editing and scrutiny by all contributors. Following the signing off of the plaintiff’s and defendant’s reports, these will be submitted to the court and exchanged between the two legal teams.  The ability for each side to find weaknesses in each other’s technical or legal arguments will act as the first test of the strength of the two opposing cases.

Depending on the nature of the case, the court may decide that the case proceeds either to trial – or arbitration as appropriate. In some cases, pre‑dating contracts between the two parties may stipulate that disputes be settled via binding arbitration. In other instances, both parties may choose for binding arbitration in preference to a trial.

Dispute resolution is an area where the law differs significantly between countries. In the US, it is common for patent disputes to be heard in front of a jury – while in most European countries patent disputes are often determined solely by a judge. I have acted as an expert in both the US and Europe and while the systems do have significant differences, there are similarities.


Following the first exchange of legal arguments and supporting expert opinions, it is common for the plaintiffs’ and defendants’ attorneys to take depositions from each other’s expert witnesses.

The ‘taking’ of depositions form part of the pre-trial discovery process and involves an attorney or attorneys interrogating and asking questions of the opposing sides’ expert witness – a process that may last several hours (albeit with comfort and refreshment breaks). If one side has engaged more than one expert witness, multiple depositions may be taken. This question and answer session is normally video recorded – along with a full transcript being prepared by a court stenographer. Your attorneys will be present during the deposition hearing, but will not be allowed to enter dialogue with you – or help you answer any of the questions. They are however permitted to record an objection if they believe a question to be unfair – and this may later be brought to the judge or arbitration panel for consideration as a matter for concern.

Preparation ahead of a deposition is crucial. In the weeks leading up to my first deposition, my attorneys explained the process for how depositions may subsequently be used in the case as evidence: The first key point to note is that the opposing legal team may at a later stage play back in court or quote anything the expert witness has said to discredit an argument being put forward. Nothing you say will be able to help your side; you cannot score points – and so your role as an expert witness during the taking of a deposition is to act as a ‘goal keeper’ – and not say something that can be used against you later on.

The questioning attorney may adopt a number of tactics including for example: appearing to be very friendly to lull the witness into a false sense of security; trying to take some quote out of context – or distort something you may have said in your expert witness statement – (or indeed a publication you may have previously written some time earlier), to try to undermine your credentials as an expert witness – and similar.

However, the good news is that with prior understanding of the potential tactics, preparations can be made to defend against most of these tactics.

Your own attorneys will help prepare you, by anticipating some of the questions you might be asked, as well as role playing in the place of the others team’s attorney.

It is crucial to remain on your guard and to be aware of possibly being coerced into agreeing with the opposing attorney’s argument through a series of questions each of which may seem innocuous. One attorney explained it to me like this:

‘If you think you may be being tricked into agreeing to a statement that could be at risk of being taken out of context, such as for example, ‘What is the color of the New York taxi in this photo – it’s yellow don’t you agree? ’ – and you fear that by agreeing you may have your words mis‑represented, then your response might be “Well it depends on what you are looking at – I can see silver door handles, black tires” etc, etc. In other words, try to neither agree or disagree with something you suspect may be a leading question, but rather be equivocal to side step the issue. This type of response can rarely be used in court against you.

Sometimes it is however very hard to disagree with something that seems irrefutable. I remember an attorney asking me asking me to agree with a statement I had made years earlier in a textbook I had written ‘that it is good laboratory practice to have laboratory note books signed off and dated each day by a laboratory manager for validation of dates for verifying priority claim dates for invention’. I could not dispute I had written this – and when asked in a very friendly manner, I had to agree this would indeed represent good practice. I smelled a rat…. As suspected, I was being invited to walk into a trap.

The attorney changed his line of questioning and followed with many other un-related and seemingly innocuous questions – and all this time I wondered whether I had somehow made some terrible mistake or ‘let a goal through’ without realising it.

More than an hour later, the attorney returned to the subject and presented to me some computer data outputs with the times and dates recorded electronically – and then invited me to agree that since these did not have a human signature, they could not be counted as being verifiable. It was at this point that I then realised the approach being used; I calmly stated that each set of data had a computer generated electronic signature and date, all of which were referred to in the accompanying laboratory notebooks which in turn weredated and signed off by a supervisor. He tried several times asking the question over and over again, hoping I might become flustered and say something to the contrary, but I simply and calmly reiterated and re‑explained that a computerised record of the instrument from which the data came was an electronic signature and could be considered even more traceable than a human signature since this could not be altered or tampered with in any way. He eventually moved on, knowing he had not managed to make me inadvertently agree to something that could be played back in court to discredit my testimony.

The preparation my attorneys gave me was truly invaluable and as an expert witness, I always ask my legal team to keep working with me until I and they feel completely comfortable with all aspects of the arguments I have to defend.

If you have to give evidence in the form of a deposition or indeed take the stand in court, having the inner confidence that comes from knowing you are well prepared, will make it far less likely that you will be made to feel nervous by an opposing attorney’s questioning.

Preparation for an Arbitration Hearing or Trial:

Once depositions have been exchanged, a period of several weeks (or sometimes months) often follows before a case proceeds to either arbitration or trial.

Prior to the court or arbitration hearing, an expert witness may be asked to spend several days or even a couple of weeks or more working intensively and closely with the legal team (normally at their offices). Expect this preparation time to be intensive, with 14-hour days in the office not being uncommon – along with takeaway food being brought into the office to allow for round the clock working!

One approach that has always helped me to keep focussed during these preparation periods is to keep in mind a sense of mission – and the reasons for accepting the assignment in the first place; your role as an expert is to be of support to the attorneys, who in turn are there to represent their clients businesses, careers and livelihoods.

As an expert witness, you need to be as fully conversant with all of the opposing legal arguments as possible – and this is where your expert opinion and testimony contributes to your side’s legal arguments. It is crucial that as an expert witness, you ask your attorneys for any explanations for points of law – or indeed any other nuances in which you may be unsure. In turn, it is key that the lawyers help ensure the expert witnesses are okay with every aspect of the case and that any legal terms or expressions that they may be very familiar with are fully understood by the expert witness(es). In a similar manner, it is the responsibility of the expert to ensure that the legal teams receive very clear scientific or technical advice in a way that can be easily understood – and indeed rehearsing these explanations will often help an argument to be polished and more easily understood.

It was said to me by a managing partner in a law firm, that no attorney should ever ask a question in the courtroom to which they do not already know the answer – and so the next stage of the preparation is often for your attorneys to prepare questions and answers they will put to you during the trial or arbitration hearing. I have found this part of the process analogous to learning lines in a play – with practice, practice and still more practice for helping rehearse the arguments, which in turn will help overcome nerves when on the stand.

Your legal team of course will help anticipate likely lines of cross examination – and while it is not of course possible to predict every question, preparation will again really help you be ready to answer any question an opposing attorney might ask of you.

If I have any advice of how to approach the day of deposition, it is to stay calm, speak slowly (this is something I need to always remind myself of!) – and not be afraid to ask the attorney to re‑phrase a question, if you do not understand what is being asked – and then to take a few seconds to reply to each question as this allows you to formulate your thinking and help prevent you saying something hastily you later regret.

Another experienced attorney reminded me that as an expert witness, you have a far greater understanding of the underpinning scientific, technical or professional practice knowledge than the opposing attorney questioning you; if you remember this truth – then your confidence that comes from this will shine through – and will be picked up upon by the judge, jury or arbitration panel.

At the time of writing, I have been extraordinarily fortunate in that every case I have acted as an expert witness has been settled with a judgment or settlement in favour of my attorneys’ side. I would not wish to attribute this in any way to myself; my role has always been there to support my attorneys and we have worked as a team. I would, however, say that by first undertaking my own careful due diligence prior to accepting an assignment and being prepared to work intensively with an unparalleled attention to detail as part of a team when called to, success is far more likely to follow. Should a case not be settled in favour of your side, then if you are confident that you executed your role as an expert diligently, do not take it to heart; remember no lawyer will win every case during their career.

Finally, it is worth mentioning that you will be paid handsomely for this work – very handsomely… but in my experience, longer term rewards often outweigh this. Remember, I earlier said that this type of work has opened many doors for me in my career. There are many examples of this; in two instances, following successful outcomes for example, companies for whom I helped support as an expert witness offered me sponsorship for ongoing research. It should also be remembered that the outcome of corporate or professional practice cases frequently affect global market sectors – and this in turn reflects on your professional standing in your field.  Lastly but certainly not least, you may be satisfied in the knowledge that comes from knowing that you have helped justice be done with the impact this has on real peoples’ lives.

Final Thoughts:

While expert witness work is certainly not for the faint hearted and can at times be quite intensive, it can also be hugely rewarding and even fun – I am deeply grateful to my former (now retired) colleague who first recommended me as a prospective expert. I hope these shared experiences will help both prospective experts preparing them for what to expect – and in turn that these insights might help attorneys select and support their own expert witnesses…. What can I say – a complementarity (if not marriage) made in heaven…. I promised before ending this article to come back to the Agatha Christie conundrum in the play for, ‘Witness for the Prosecution’; now that you have read to the end, I had better keep my promise. For those familiar with the plot (and without giving a complete spoiler for others who have not), had the defense engaged forensic experts, then the case would have collapsed and the true murderer might have been brought to justice – but that of course would have spoiled the story….. !

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