It is said that Abraham Lincoln, as a young attorney in Illinois in the 1830s, had for one of his first clients a man called Armstrong who stood accused of murder.
During the trial the chief prosecution witness declared he had observed the crime being committed by the prisoner. When asked how he had been able to see it in the dark, he said the moon was shining brightly.
"You are sure?" asked Lincoln, and was told "I am". The attorney then produced a book and said to the jury: "This almanac, which lists the phases of the moon, proves that no moon was shining at the time my client was supposed to have been seen committing murder; this witness cannot be believed". And Armstrong, whom everyone had expected to be hanged, was freed.
Lincoln in his role of advocate used the kind of expertise often provided nowadays by meteorologists when they act as "expert witnesses".
Today's exponents, however, have more information at their disposal than that available from penny almanacs; they have a wealth of weather records, which may assist in the apprehension of a culprit, or in the apportioning of blame in court. In practice, meteorology in this guise is more preoccupied with routine civil cases than with the more sensational world of criminal law.
Suppose, for example, that one of the parties to a motor accident maintains that the road was wet at the time of the occurrence, or that there was frost, or the setting sun interfered with normal vision. By examining the weather charts, a meteorologist may be able to refute or confirm contentions such as these.
Similarly in the case of alleged storm damage, the expert can provide objective evidence. He or she will be able to say if the winds were quite exceptional, or if they were not as strong as some of the parties might suggest.
In criminal law, the meteorologist is less often in demand, but there have been instances when weather evidence was crucial. In a case in Canada, for example, the body of a murder victim was not found for some time after the crime had taken place, and the main suspect had strong alibis for much of the intervening period.
But careful reconstruction, with the help of a climatologist, of the exact temperature pattern in the two days before the discovery of the body made it possible to calculate the precise rate of cooling of the body.
This allowed forensic scientists to pinpoint the time of death to within two hours, to a time for which the suspect had no alibi.