EARLIER this month Sheriff James Scott sparked outrage at Edinburgh Sheriff Court when he sentenced a motorist convicted of causing the death of 75-year-old cyclist Audrey Fyfe to 300 hours of community service and a five-year driving ban.

Cycling campaigners branded the sentence as "scandalous" and warned that it would discourage others from taking up the activity.

The Crown Office is still considering whether the sentence was "unduly lenient", but one aspect of the case reignited a particularly divisive issue: whether cyclists should be bound by law to wear helmets.

While Sheriff Scott stated that Mrs Fyfe "wasn't to blame in any way for the accident", the fact she was not wearing a helmet at the time of the collision in August 2011, in his view, "contributed to her death". For many in Scotland's cycling lobby – the majority of whom oppose any attempt to dictate helmets by legislation - the remark struck an uncomfortable chord. Would the same have been said if Mrs Fyfe were a motorist instead, choosing to drive a small car, more vulnerable to impacts? Would that personal choice have been considered a factor in her death if she had been struck by a heavier, more powerful vehicle? It seems unlikely. And yet, by choosing not to wear a helmet she is handed a degree of responsibility for her death. For cyclists, the case brought into sharp focus their sense that not all road users are equal.

But what if helmets were imposed by law? Evidence shows helmets cut the risk of injuries to the brain by around 88%, but would legislation drive a reduction in the toll of cyclists injured on Scotland's roads? A study conducted in Canada and published in the British Medical Journal this week sheds some light on the debate, with some unexpected conclusions.

Canada is among a handful of countries to have passed legislation requiring cyclists to wear helmets. Between 1993 and 2003, six of the 10 provinces in Canada implemented bicycle helmet legislation. Researchers tracked admissions to hospital for cycling-related injuries between 1994 and 2008, to assess the law's impact.

They recorded 66,716 such hospital admissions throughout Canada during those 15 years. Head injuries accounted for almost a third (30%) of admissions, and three in every four cyclist deaths. However, the rate of cycling-related head injuries among children and adolescents fell 54% in provinces with legislation, compared to around 33% in provinces without helmet legislation. Among adults, there was a 26% decrease in provinces with the legislation against a "negligible increase" of 0.1% in provinces without.

At face value, a clear case in favour of legislation – and yet the researchers conclude that its impact "seems to be minimal". Boiled down, they couldn't prove an independent link between the declines and the legislation. Admission rates were already falling, and other factors such as public safety campaigns and changes in cycling infrastructure – traffic calming measures and more designated cycle lanes – appeared equally, if not more, responsible.

So while their use "should be encouraged", as the researchers state, maybe all road users needs to be less worried about helmets and more concerned about the roads themselves.