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Meteorology in Legal Cases


by John Coates-Greetham, Forensic Meteorologist with over 30 years experience 1984-2014


On being instructed by a solicitor, the forensic meteorologist carries out an investigation into the weather over a few hours, days and on occasions over many months or even years. One such case used daily rainfall data over a forty year period.

Why do the courts need an expert in meteorology? Although meteorology is an every day science, in that almost everyone understands the terms, fog, snow, rain, hail etc. the forensic meteorologist is required to examine weather records and offer an opinion based on the weather data and the science. This, almost always, involves preparing the equivalent of a weather forecast, (backcast ). He is required to explain to the court why, when and where the weather occurred and how it affected the incident.

The role of the meteorological expert witness is the same as any expert witness: To give an honest and unbiased opinion based on sound scientific principles with supporting data and references to publishedwork and years in the field of meteorology.

The meteorologist's part is to describe to the court, by means of a written report and if required verbally in the witness box, the evolution of a weather event

From the records, witness statements and other sources the meteorologist gives an opinion on any matter concerning the weather that affects the case. For example it may be a question of how much rain fell, how strong the wind was, what time ice formed. On some occasions a forensic entomologist needs to know the weather over a number of days. on one occasion the temperature and humidity was used to assess the effect of the weather on the development of fly larvae in a body lying in the open.

The weather is a matter of record and is well documented, not only in the weather records, but in the case of severe weather events and often road traffic accidents, in newspapers, on television, in witness statements, etc. Although there is a time element involved, the changes of the various weather parameters in terms of time are fixed. It is therefore a problem of spatial separation of the weather events at the nearest weather stations and the weather at the site of the incident that the expert has to consider. The opinion is based on weather data from a variety of sources, the internet, the Met. Office, witness statements, the media and on some occasions CCTV from the site of the incident.

Instructions should include all the information available where the weather is referred in the form of statements, photographs, CCTV if available.

Although meteorological evidence is not vital in many cases, occasionally it is very important. Such a case was R V Agis. Mr Agis was the designer of a large plastic multicoloured structure through which the public walked listening to music. The structure was tied down by ropes pegged into the ground. He was charged
with manslaughter as well as breaking health and safety rules. The structure lifted off the ground in a park at Chester-le-Street injuring twenty or so people
and killing two. Meteorological experts were employed by the prosecution and defence..

The case was heard in the Newcastle Crown Court. The expert for the prosecution gave as his opinion that the cause of the accident was a strong gust of wind
which should have been anticipated. CCTV was available throughout the day. The day was very hot, sunny with very light winds until about one minute before
the structure rose vertically into the air. Trees near the structure suddenly showed violent movement whilst other trees further away were generally still. Some of the nearest weather stations did show quite strong winds at times, others light winds. The site of the incident was much more sheltered from the prevailing
wind than the weather stations and CCTV from the site showed very little wind.

The meteorologist ( Coates-Greetham ) acting for the defence disagreed with the prosecution expert on the wind theory. The defence expert’s theory was that the top surface of the plastic structure became very hot. This caused air to rise over the structure in a strong thermal and the structure was sucked off the ground. The sudden increase in wind over the nearest trees supported this theory as air rushed in to replace the rising air. In the event the expert for the defence was not called to give oral evidence. It appears that the CCTV evidence was conclusive in destroying the wind theory. The jury could not agree on a verdict and Mr. Agis was found not guilty of manslaughter but guilty of breaking health and safety regulations on a majority verdict.

In Goodes v E. Sussex C. C. ( House of Lords Appeal June 2000 ) the weather too was important. The claimant skidded on ice whilst overtaking and crashed into the wall of a bridge and suffered severe injuries. A weather report showed the high probability of the presence of ice on road surfaces which would have been obvious to drivers due to hoar frost on grass and trees. The claimant lost in the high court won the appeal court and lost in the House of Lords.

Coates-Greetham was started by John Greetham after a career in the Met. Office spanning thirty seven years 1951 to 1988. Starting as an observer then forecaster and eventually in 1986 head of the legal enquiry section as a Senior Scientific Officer. Over the last 30 years in the private sector, reports have been
submitted in both civil and criminal cases. Cases have covered a very wide spectrum from murder, rape to minor traffic offences, on the civil side, personal injury, road traffic accidents and building delays covering many months. His first court appearance was in 1984 one month after joining the enquiries section. The case was one of murder. A taxi driver was killed when a rock was thrown off a bridge during the miners strike of 1982. A policeman had given evidence that he saw the accused by bright moonlight on a cloudy night with light drizzle. His evidence was withdrawn.

Reports, prepared by Coates-Greetham, have covered the weather in Bangladesh, The West Indies, Bulgaria, Romania and at 37,000 feet over the Eastern Atlantic just off West Africa, 14,000 feet near Chicago, and other cases at flight level concerning injuries to cabin staff due to turbulence.

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