Who would be an expert?

OUR SOCIETY is heavily dependent on technology and so it is inevitable that litigation will arise in which technology is involved. On the other hand, technology is only one out of the great variety of subjects with which the legal system has to deal.

The police find themselves in a similar position, where the range of topics an officer has to study leaves little time for technical matters. Not much technology is needed to arrest a football hooligan, whereas measuring the speed of cars, for example, is a different matter.

Sympathy must also go out to patent agents and patent officers, who are faced with purported inventions over fields so wide that they cannot be familiar with all of them.

This is the environment that creates the need for technical experts, although it doesn’t shed much light on what an expert is. We don’t usually wear uniforms or protective clothing and are difficult to spot in a crowd. An expert might loosely be described as someone who advises the legal and/or intellectual property professions about technology. For the purposes of impartiality when litigation is involved this definition is refined to be someone who advises the court.

Conflicting interests

My own impartiality is actively defended, and before taking on any matter I enquire who the parties are in order to avoid any conflict of interest. Out of all of the various reports I have been asked to write in support of litigation, I don’t think I would have said very much different if I had been working for the other side.

On occasions I have found my services no longer to be required when a draft report contained some unfortunate truths.

In some litigation, the correct operation of a piece of technical equipment is being challenged. I have watched with concern when one party appoints an expert who is an employee of the manufacturer of said equipment. In no way can bias – witting or unwitting – be excluded when there is a conflict of interest of this kind. And having listened to the evidence given, and found it on occasions to be contrary to the laws of physics, I can assure the reader that bias is a difficulty in such cases.

In order to advise, the expert must have adequate knowledge of the subject and be able to explain it.

The latter is very important as knowledge that cannot be passed on isn’t useful.

Thus, it is almost axiomatic that an expert should have a high profile in his field, if not to the public at large. He might have written books or papers that are widely acclaimed; might perform research and lecture regularly. One could argue from the other direction that in the absence of such a profile the legal profession would not be aware of the expertise.

The ability to answer the questions of an audience is useful grounding for giving evidence from the witness box, although few audiences will match the hostility of a thorough cross-examination.

Presenting a consensus In my view one thing an expert should not do is bring to the court unproven pet theories of his own.

There have been some well-publicised failures in this regard which have done the image of experts no good. I regard such actions as showing a lack of impartiality. A technical expert’s role is to bring to the court, wherever possible, theories that represent the broad view of those working in the appropriate field, that can be supported by references and proven by experiment.

If such proof is not possible the expert must make it clear whether what he has to say is the consensus of those skilled in the art or is his own view. In my own reports I like to make clear distinctions between the facts I have discovered, my logical analysis of those facts, and any opinions I may form as a result.

It was never my intention to become an expert witness; all I did was to write the book that I couldn’t buy when I was trying to understand an emerging technology. The Art of Digital Audio contained a detailed description of the laser optics of a compact disc. When the CD became a commercial success, everyone and his dog claimed to have invented it and I was asked to be involved in a number of intellectual property actions.

There have been a fair number of books since then, details of which can be found on the Focal Press and Elsevier websites.

While we have looked at some of the attributes of an expert, that falls short of a definition. The best definition I have come across is that an expert is someone who can assess the merit of information put before him. Such information might take the form of a patent. The key merit of a patent is its validity. Perhaps another definition of an expert is someone who finds the least novelty in a patent.

I assess information all the time, sometimes without realising it. In short, if a new piece of information contradicts what I already know or violates the laws of physics, then I become suspicious. It is possible that what I know is suspect, but then each step of my learning has been based on the same process.

Starting from basics, it is possible to work logically forward to conclusions about technology taking small and provable steps. A book written in this way will be highly understandable because explanations are far more powerful than facts.

In one case where I became suspicious about information put to me it slowly became clear that the only explanation for what I was seeing was systematic tampering with evidence.

The laws of physics The laws of physics differ from the laws of the realm in that they are deduced from repeatable experiment.  I can prove Ohm’s Law on my kitchen table any time I please. No one has yet shown it to be false. I would argue that Ohm’s Law has always been true. It is just that mankind didn’t realise it until Ohm made a few connections.

Knowledge of basics has some side-effects. I can’t read a hi-fi magazine without falling about laughing. One is typically exhorted to buy fantastically expensive loudspeaker cables that purport to have some mystical attributes because they are made from oxygen-free copper or because the insulation is hand-knitted by Peruvian virgins. In fact the only attributes such products have is the ability to extract money from the gullible. Of course, making unsupportable claims for hi-fi equipment does little harm to society at large, whereas when such claims are made for equipment used for forensic purposes I cease smiling in an instant.

On the other hand, a grasp of basics allows a wide field of endeavour to be understood. The principles of wave motion do not differ between laser optics, radar and acoustics. The concept of reflected impedance explains induced drag just as well as it does regenerative braking. The concept of transforms is in common use for analysing audio signals, but it is also used to analyse the behaviour of helicopter rotors as well as being used in MPEG image compression. Acoustics and aerodynamics have a great deal of overlap.

It has been my experience that the more interesting a machine gets, the more likely it is to embrace multiple disciplines. The proper explanation of how a flyby- wire airliner makes an instrument landing holds my personal record for engineering disciplines.

A matter of statistics Knowledge of statistics is important to the work of a technical expert.

Nothing can be made that is perfect, and one doesn’t expect that. Instead, one expects means to minimise imperfections, guidance so that circumstances in which imperfections show may be avoided, or honesty when there are imperfections. Statistically speaking, it is impossible for all speed cameras to work properly all the time. Some will fail to catch motorists who are speeding and some will catch motorists who aren’t. We don’t know about the former, but we do know about the latter.

Many phenomena display what are called Gaussian statistics, where the measurement is in error by a random amount that can be above or below the true value. The probability of occurrence of the error decreases with its magnitude. Such errors can be due to noise in optoelectronic systems, such as in laser rangefinders. The solution is to average a lot of readings: if the error is Gaussian, it will average out.

However, on a clear day light travels substantially in a straight line from a laser rangefinder to a target and back again. Conversely, if the air is hot and turbulent, the light path gets longer by a random amount. There is no mechanism for the path to get shorter. Clearly, the statistics are not Gaussian, and averaging cannot eliminate the error.

The skilled person would know not to use laser range-finding under certain conditions, such as when obvious miraging is visible.

The unskilled user may or may not know, depending on whether or not any training courses or instruction manuals included the topic.

Where a piece of equipment is specifically intended for use by the police to provide evidence in a court about the speed of a vehicle, for example, the reasonable person would expect that the approval process carried out by the Home Office would identify such circumstances and there would be suitable wording in the training material.

In my experience the reasonable person might be disappointed.