Excerpts from Lord Neuberger’s speech to the Royal Society on Science and Law delivered on 24 November 2015.

This speech is worth reading in full because it offers a careful comparison and contrast between legal method and scientific method.

9. …there are some fundamental similarities between scientific and legal thinking – not surprisingly as their aims are in some ways similar and they are each the product of human intellectual endeavour.

On a relatively high level of analysis, science and law are both concerned with imposing order on chaos, and identifying laws which work – in the one case with the observable universe, and in the other case with human beings in society.

And both scientific thinking and legal thinking rely in general on logical reasoning and on the evaluation of evidence. Scientists and lawyers each search for and assess hard facts from which they can establish the truth, whether of a particular theory or in a particular case, and they each use principles and reasoning to enable them to reach what they hope is the right conclusion. A law student no less than a science student learns to assimilate what are seen to be the currently significant facts, theories and hypotheses, and the currently important issues and principles, as well as how to question and reason, and how to look for and assess evidence.

10. Nonetheless, there are many significant differences between a professional scientist’s approach to a scientific problem and a judge’s approach to a legal dispute. As I have mentioned, the justice system and scientific method are both designed to get to the truth.

However, as has been fairly pointed out, there are real differences in approach.
Scientists observe the facts, form a hypothesis, and then test the hypothesis with experiments in order to establish a hitherto unknown law.

On the other hand, a legal dispute appears to proceed on an almost reverse basis; a legal case starts with already established laws, which each party applies to a series of facts with a view to creating a hypothesis, which then becomes that party’s case, and the judge then decides which of the two cases she prefers.

And the validity of published scientific discoveries can be confirmed or falsified by repeating the published experiments, whereas the best the law can do about judicial decisions is a sort of peer review, namely by way of an appeal to a higher court; and as a recent study in the journal Nature showed, peer review is not always a guarantee of accuracy.

13. It is also worth mentioning the contrasting role of common sense in scientific and legal thinking. It is more than twenty years ago that Lewis Wolpert convincingly demonstrated how many well-established scientific principles are positively contrary to common sense…
By contrast, lawyers frequently rely on common sense – for instance, to take just a few examples from recent Supreme Court cases, in deciding what a commercial contract means, in assessing whether particular damage or a particular death was caused by a particular action…

14. By the same token, logic is absolutely fundamental to all scientific endeavours. A flaw in the logic of any step in a chain of reasoning of any scientific hypothesis will be fatal to the reliability of the hypothesis and to any conclusion it would otherwise appear to justify.

By contrast, while logic undoubtedly plays a very important part in legal thinking, the precise extent of its role is uncertain. Indeed, a cynic might say that judges generally invoke logic to support a conclusion, but when they dislike the conclusion which appears to be compelled by logic, they fall back on common sense or human experience.

He goes on to speak about different approaches that can be taken.

19. Another feature which scientific and legal thought processes share is the reasoning process. Karl Popper, with his theory of “critical rationalism”, helped to explode the notion of a scientist carefully and logically working his way from the known A to the unknown Z. Popper thought it more likely that a scientist has a bright idea, Z, and then tries to rationalise backwards to A to justify it – and then tries to see whether it works, normally by falsification. In truth, I suspect that the processes of scientific discovery and invention involve a mixture of thought processes – reasoning backwards as well as forwards.

A judge does the same. Once she grasps the facts of a case, she often has an instinct for the right answer, and then tries to work out logically whether it is the right answer, and if so why. Of course, like a scientist, a judge may often have a change of mind as to the right answer or may decide that what she thought was the right answer cannot be justified as a matter of law. The similarity of thought process in science and law is scarcely surprising, given that they are both fields involving human endeavour.

20. The fact that there are no right answers is nonetheless more likely to be true in law than it is in science, but scientists have an enormous advantage over judges. When faced with a problem, a scientist can respectably say “It’s impossible to give an answer”…

A judge has to give an answer at the end of a case, and, far from demonstrating professional high standards, a judge who said at the end of a case: “It is impossible to give an answer” would be thought incompetent. And, at least under our common law adversarial system, a judge cannot insist on calling more witnesses, let alone carry out her own investigation of the facts.

Edited for ease of reading.
You can find the full speech at the Supreme Court website: https://www.supremecourt.uk/