Driving and Dementia

There is a ongoing trial in Cambridgeshire at the moment, which is all kinds of tragic:  an elderly lady prosecuted for causing death by careless driving, following a fatal road collision involving five-month old Louis Therold and his mother, Rachael.  I cannot imagine what Mrs Therold and her family must be going through after the loss of an infant in such circumstances.  The legal issue now at stake in this case, shortly to be considered by jury, is whether or not 75yr old Shelagh Robertson was legally insane at the time of the incident.  She has pleaded not guilty by reason of insanity and the jury will shortly consider whether or not that defence succeeds.

The medical case behind that defence is that Mrs Robertson was suffering from undiagnosed dementia at the time of the collision and whether the degree of that condition was sufficient to mean that she “did not know what she was doing or did not know what she was doing was wrong” because of her illness.  Since the incident, she has had medical assessment which confirms her diagnosis, but it remains for the jury to decide whether all of that amounts to an insanity defence, on the balance of probabilities.


I’ve covered insanity in some detail on the blog before, this post is merely a reminder in the context of this more recent and tragic case.  Where someone is charged with a criminal offence, it is open to them, if they believe the grounds are met, to argue that they should not be held criminally responsible because they did not know what they were doing or did not know what they were doing was wrong.  This can become complicated to understand, not least because insanity is about someone’s illness or mental state at the time of the offence, in contrast for example, to someone’s cognitive ability at the time of their trial.  Being unfit to plead is a separate matter entirely.

In the present case, Mrs Robertson is obviously fit to plead and stand trial, because it is ongoing: she is submitting that at the time of the incident, she was legally insane and this is now for the jury to consider.  The prosecutor accepted that there is no doubt about her suffering a form of dementia, including shrinkage on the brain in the area associated with memory and language.  The question, he contends, is “where on the slope of dementia Shelagh Robertson was in January 2021?  It’s not just a question of whether someone has dementia; it’s a question of how bad is it.”  The judge in the case, in summing up, told jurors that to return a verdict of not guilty be reason of insanity, they must be satisfied, on the balance of probabilities, that Mrs Robertson had dementia at the time and either “did not know what she was doing or did not know that what she was doing was wrong.  This doesn’t include a momentary failure to concentrate”.

So the degree of someone’s condition matters, also.  Having dementia (or shizophrenia, ADHD or bipolar disorder) is not of itself enough to ensure an insanity defence – it is about how badly that condition affects someone’s ability to function.


It will be interesting to see the sentencing in this case, because it has been accepted that Mrs Robertson’s driving fell below the required standard.  So either, she will be convicted of the offence and sentenced accordingly; OR, she will be cleared because of proven insanity and a relevant order will have to be made as a result.  In other cases where dementia has been the medical condition behind a trial affected by the defendant’s cognitive functioning at some point between incident and proceedings, it gets very sensitive, not least because defendants with such conditions are often elderly and always vulnerable, regardless of the nature of the allegation.  Normally, consideration can only be given to either a) hospital order (with or without restriction under s41 MHA); a supervision order (under the Probation Service) or an absolute discharge which means the outcome of the court process if formally noted but no specific criminal justice or health outcome is imposed.

You don’t recover from dementia as I know from relatives who were affected by it – but you do have some days or parts of days that may be said to be better than others.  One particular consideration in this case, is the fact the jury are being invited to make their assessment when it is known there was no formal assessment or diagnosis in place at the time of the incident where poor Louis died and his mother was seriously injured.  Some commentary on social media painted Mrs Robertson as just another driver trying to get away with killing people by “playing the dementia card”.  This strikes me as a little unfair, now we know Mrs Robertson has been diagnosed but then this is a pejorative thing we hear with many prosecutions where mental health or cognitive conditions are raised as being relevant to the defendant.

These are always difficult cases: but it’s worth bearing in mind the point about what insanity means:  simply, that someone has an impairment so serious that they were not criminally responsible for their actions because of the degree of their condition.  They did not know what they were doing or did not know what they were doing was wrong.

UPDATE: the jury did find Mrs Robertson not guilty by reason of insanity.

Winner of the President’s Medal,
the Royal College of Psychiatrists.

Winner of the Mind Digital Media Award


All views expressed are my own – they do not represent the views of any organisation.
(c) Michael Brown, 2022

I try to keep this blog up to date, but inevitably over time, amendments to the law as well as court rulings and other findings from inquests and complaints processes mean it is difficult to ensure all the articles and pages remain current.  Please ensure you check all legal issues in particular and take appropriate professional advice where necessary.

Government legislation website – www.legislation.gov.uk