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How John Smeaton helped transform expert testimony

20 May 2024

In 1782, John Smeaton’s evidence on the decay of Wells Harbour marks the formal beginning of the scientific expert witness.

How John Smeaton helped transform expert testimony
John Smeaton was often called to court to share his scientific expertise. Image credit: ICE Library

By the 1780s, John Smeaton was a well-connected and highly regarded figure in mid-18th-century scientific circles.

Due to his reputation, Smeaton was often called to court and before Parliament as a scientific consultant.

Smeaton was most known for specialising in harbours, which led him to play a central role in the rise of the expert witness.

Folkes v. Chadd

The first case in which Smeaton acted more as a witness than an arbitrator, as he’d previously done, was Folkes v. Chadd.

The case was about the Wells Harbour channel in Norfolk and the surrounding salt marshes, where embankments had been built to protect the land from tidal flooding.

The harbour had decayed, and merchants and shipbuilders entered a subscription to build sluices to control the flow of water, and save the harbour.

In 1777, a recently built sluice was destroyed by a storm.

Frustrated, commissioners of the harbour wished to remove the embankments which they thought was the true cause of the harbour’s decay.

The then owners of the embankments and surrounding land, Martin Browne Folkes and Robert Hales, brought an action of trespass against the commissioners of the harbour, represented by George Chadd.

What caused the harbour's decay?

Ultimately, during a series of trials, the central issue of this case became whether the embankments were responsible for the decay of the harbour or if the harbour’s decay was a natural phenomenon.

Should the decay be natural, Folkes and Hales would bear no responsibility and be allowed to keep their embankments.

It was this question, effectively on the science of the harbour’s decay, that a man such as Smeaton seemed especially well-qualified to answer.

The problem with expert testimony

The problem facing the would-be expert witnesses was that they were informing the court of their opinions, often based on theories that weren’t directly linked to observations.

The underlying principle that guided courtroom procedures was that only sense perception—observations made by the five senses—offered the kind of certainty that the courtroom demanded.

This was exactly the opposite of the nature of Smeaton’s eventual testimony.

After making initial observations of Wells Harbour, Smeaton, as a scientist, drew expansive theoretical connections about the effects and cause of the harbour’s decay.

So the court had to determine if Smeaton, due to his expertise, would be exempted from the court’s normal rules.

Smeaton takes on the case

Smeaton was in such demand that both sides involved in the dispute attempted to hire him!

He even tried to serve as an intermediary between the harbour commissioners and the landowners hoping to find a compromise, but these efforts ultimately failed.

Eventually, Folkes and Hales secured Smeaton’s employment and so Smeaton set out to complete his investigation of the principal cause of the harbour’s decay.

Smeaton submitted his report on 4 May 1782.

A plan of the Port of Wells, from Smeaton's report. Image credit: ICE Library
A plan of the Port of Wells, from Smeaton's report. Image credit: ICE Library

Smeaton’s report

In keeping with his reputation, Smeaton’s report was well organised, clearly reasoned, and expansive in its findings.

It found that the harbour’s decay was predominantly natural.

Smeaton also found that the commissioners of the harbour could’ve saved the harbour through ‘industry, art, and the hand of man’.

However, the sluice they had built was of poor quality and not used with enough frequency.

In short, Smeaton’s report squarely laid the blame for the harbour’s decay at the feet of the harbour commissioners.

Meanwhile, Smeaton’s clients, perhaps unsurprisingly, were completely innocent.

The court rejects Smeaton’s testimony

The following trial, which was the second trial on this issue, was held in the Court of Common Pleas before Justice Henry Gould.

Sir Henry Gould by Thomas Hardy (1794). Image credit: The Art Institute of Chicago (CC0 public domain)
Sir Henry Gould by Thomas Hardy (1794). Image credit: The Art Institute of Chicago (CC0 public domain)

Smeaton’s report, along with the other experts involved in the trial, was submitted to the court record and circulated to the jury before the trial.

Ultimately, Justice Gould found that Smeaton’s report should be thrown out and he couldn’t be called to the stand as Smeaton’s testimony was based entirely on speculations.

'Men such as Smeaton know best' – the formal acceptance of expert testimony

The Folkes and Hales legal team appealed Gould’s ruling to the King’s Bench, under the leadership of the reformist Lord Mansfield.

They asked to address the specific issue as to whether Smeaton’s testimony and report was proper evidence.

Mansfield took the opportunity not just to rule on this case but to expand the rules of evidence.

Mansfield’s ruling is vividly captured in the 1831 published account of the trial by Henry Roscoe.

Earl Mansfield by Francesco Bartolozzi (1786). Image credit: The Art Institute of Chicago (CC0 public domain)
Earl Mansfield by Francesco Bartolozzi (1786). Image credit: The Art Institute of Chicago (CC0 public domain)

Roscoe used the partial notes of the then-present court reporter Sylvester Douglas, and attributed the following words to Mansfield:

It is objected that Mr. Smeaton is going to speak, not as to facts, but as to opinion.

That opinion, however, is deduced from facts which are not disputed- the situation of banks, the course of tides and of winds, and the shifting sands.

His opinion, deduced from all these facts, is, that mathematically speaking, the bank may contribute to the mischief...

In matters of science no other witness can be called…Of this, such men as Mr. Smeaton alone can judge.

Lord Mansfield

With Mansfield’s ruling on 21 November 1782, the court formalised that expert testimony was not just proper evidence, but the best kind of evidence for the court to consider “in matters of science”.

It was the clarity and persuasion of Smeaton’s reports that exemplified Mansfield’s idealised and optimistic trust in the clarifying power of scientific testimony.

The legacy of Smeaton’s expert testimony

Ultimately, the legality of Smeaton’s testimony was profound.

His esteemed background and considerable technical knowledge confirmed to the court that science has a place in the courtroom.

His testimony cemented a trend of interested parties bringing forth their own expert witness, who, with the authority of the scientific method, could and would assert the correctness of their client.

It’s precisely this ambiguous legacy that makes remembering the beginnings of the expert witness, and Smeaton's central role, so important.

  • Alexander M Aizenman, doctor of philosophy (DPhil) student at the University of Oxford