Little was known about Michael Connelly. Not even his surname was really known: some spelled it Connelly, but others insisted on Connolly, or even Conly. It was easier to refer to him by his nickname: Old Mick. What was known was that, at some point in his life, he had turned his back on society, becoming a hermit. He lived quite happily in a tumbledown hut on farmland close to Lesmahagow in Lanarkshire – near the road that linked Carstairs to Lanark. He had a small pension, did odd farm jobs, and was helped by sympathetic locals who would make sure he was all right, and give him odd parcels of food or fuel to keep him going.

He lived this way until he was 79, in peaceful isolation in his tiny hut, but he was not to have a peaceful death. Instead, one night in the summer of 1952, two men robbed him of what little money he had, together with his socks, tearing off his boots to get to them. They then hit him with a brick, an iron bar and a bottle, leaving him bloody and dead, sprawled across his bed.

It didn’t take long for the men in question to be apprehended and charged with Michael Connelly’s murder. George Francis Shaw, aged 25, a farm worker originally from Ireland, and George Dunn, a local man aged 22, were the suspects. They were put on trial, but although they were found guilty, they were guilty of different offences, and received different sentences.

Shaw was found guilty of murder, and was hanged at Barlinnie in 1953. Dunn, however, was found guilty of culpable homicide, and he would live. What was the difference between them that led to this apparently different treatment and punishment? Why did Dunn get to live, whereas Shaw was sentenced to death?

The main clue lies in Dunn’s conviction for culpable homicide. This was a conviction more akin to the English conviction of manslaughter – a killing done without prior planning. Significantly, whereas murder was a capital offence, culpable homicide was not. It had been decided that Dunn’s involvement in the case involved less responsibility than Shaw’s – and this was because of Dunn’s alleged mental deficiencies.

A series of legal decisions, primarily given by Lord Deas, had resulted in a doctrine that various types of ‘mental weakness’ could reduce what would otherwise be a conviction for murder to one for culpable homicide, for which the courts had more discretion in terms of sentencing. However, in order for a defendant to have such ‘mental weakness’ (or ‘deficiency’ as it was then described), the Criminal Justice (Scotland) Act of 1949 stated that a court prosecutor had to put before the court evidence of the accused’s mental condition.

Firstly, they had to be ‘defective’ within the meaning of the Mental Deficiency (Scotland) Acts of 1913 and 1940, and to show that, two registered medical practitioners had to provide evidence of that. On such a person being convicted, the court could order that the individual be ‘removed to and received and detained in such institution for mental defectives as may be named in the order or that he be placed under guardianship’.

However, after medical evidence was duly heard stating that Dunn had a mental age of eight or under, Dunn’s counsel had tried a more novel approach in court. It was argued that if his mental age was under eight, the provision of the Children and Young Persons Act should be invoked. This was because children under the age of eight could not be put on trial, suggesting that the ‘mental age’ ascribed to Dunn may have been influenced by the Act stating that under this specific age an individual could not be tried. However, as Lord Carmont made clear on hearing this argument, it was a ‘novel’ point, which could not have been raised before the Act was passed just two years earlier, in 1950. It was also the first time such an argument had been made. Lord Carmont stated:

‘The Act referred to the age of a child in years, the chronological age. The Act referred to children, not imaginary children, the children of the imagination of doctors trying to assess feeble-mindedness. That was all the doctors were doing when they referred to Dunn’s mental age.’

Instead, Lord Carmont directed the jury that the proper verdict in this case – if they found Dunn guilty – would be to convict him of culpable homicide, ‘because Dunn’s feeble-mindedness was sufficient to diminish responsibility’.

In the event, Shaw was convicted of murder, and Dunn, because of his mental ‘deficiency’, was convicted of culpable homicide. Despite his counsel and doctors stating that he had a mental age of under eight, he was classified as ‘feeble-minded’. Under the Mental Deficiency Act of 1913, to be such was to be an individual ‘whose weakness does not amount to imbecility, yet who require[s] care, supervision, or control for their protection or for the protection of others, or, in the case of children, are incapable of receiving benefit from the instruction in ordinary schools’. Although such an individual obviously required help and care, and may have been easily swayed by others, this was the least ‘serious’ classification of intellectual impairment, and a feeble-minded individual was seen as being more able than an ‘idiot’ or an ‘imbecile’.

George Dunn, after his conviction, was sent to the State Institution for Defectives at Carstairs, under Section 24 of the Criminal Justice (Scotland) Act of 1940. Back in 1902, the Scottish press had bemoaned the growing tendency to convict individuals of culpable homicide rather than murder, sighing that ‘the old theory of a life for a life is apparently going out of date, since it is hardly possible to get the super-sensitive feelings of a Scotch jury to convict on the main plea and so order capital punishment. They always seem disposed to hearken to the humane appeals for mercy on the ground that the prisoner’s mental equilibrium has been unhinged’ (Northern Scot and Moray & Nairn Express, 20 September 1902). The feeling in Edwardian Scotland was clearly that using intellectual impairment to ‘avoid’ a capital sentence was a ruse, a means of playing to the sympathies of court and jury.

The Mental Deficiency (Scotland) Acts of 1913 and 1940 were in part a way of clearly defining those with genuine issues and limitations, but there was still some residual lack of understanding about how to determine the criminal responsibility of those who were easily influenced by others, or who had a lack of understanding about right versus wrong. How could one man be hanged for murder, when the man with him was not? The apparent discrepancy between how Shaw and Dunn were treated caused some disquiet; yet to modern eyes, it is clear that the two men were different, that they would have perceived the murder in different ways, and that they needed to be treated differently within the legal and criminal justice context. In addition, Dunn did not get a free ride. He was no free man after the conclusion of the trial: he was incarcerated.