His story has parallels with that of Erin Brockovich, whose David-and-Goliath battle against a US energy company became the subject of a Hollywood film. But unlike the American legal clerk, Liam Grant is taking on a giant pharmaceutical company.
In 1996, Mr Grant's 19-year-old son, also called Liam, was prescribed Roaccutane, an acne drug. Formerly cheerful and outgoing, he soon became withdrawn and reclusive. Four months after he started taking the drug, he was found hanging from a tree outside Dublin. A jury delivered a verdict of suicide.
Mr Grant has spent more than €1m (£835,000) of his own money pursuing the drug's manufacturer, the Swiss company Roche, and the regulators whom he holds responsible for his son's death. Roche denies it is to blame for any deaths or severe mental health problems.
He has now won a crucial ruling from the European Ombudsman, Nikiforos Diamandouros, that the European Medicines Agency (EMA) should release details of all adverse reactions to the medicines it licenses. It is required to respond by 31 July. If it complies, patients will for the first time have access to Europe-wide details of suspected adverse reactions to all medicines licensed by the EU's drug safety body.
A forensic accountant from Dublin, Mr Grant was supported by his wife, Loyola, and their three surviving children in investigating Roaccutane. When he could not persuade the company to carry out the studies he thought necessary, he funded them himself.
In 2004, he sued Roche in the Irish courts. The company responded by offering to pay him the maximum compensation under Irish law for the death of his son – about €30,000 – as well as his costs and special damages. When he refused, Roche appealed to the Irish Supreme Court to compel him to accept. In 2008, the Court threw out the appeal and ruled that his case could go ahead.
"I did this out of utter anger," Mr Grant said. "Roaccutane was licensed for the treatment of acne in 1982. Soon there were studies showing patients got depression within weeks of starting on it. When I started investigating, I was looking at 20 to 30 published studies linking the drug to depression, psychosis and suicide. Why wasn't Roche carrying out studies?
"I met with the Committee on Safety of Medicines in the UK and the Food and Drug Administration in the US. I argued that if they can give a company a licence they should be able to say, you must do these studies. They responded that they had no power to compel companies to carry out studies."
A scientist hired by Mr Grant to investigate Roaccutane found that despite the number of studies suggesting a link with depression and suicide, at the time only a handful of countries required that the drug carry warnings to this effect. Warnings were subsequently added in all countries. The drug has triggered about 5,000 personal injury claims.
Mr Grant, 61, said his professional career had helped him to keep focused on his campaign. His wife, Loyola, died in 2007. "I am not giving up now. I have spent the last 30 years as a forensic accountant investigating some of the biggest frauds in the country and preparing reports for the courts. That has allowed me to avoid getting involved emotionally and keep objective. It hasn't dominated my life," he said.
It would be "wonderful", he added, if the EMA granted public access to its documents on suspected adverse reactions. "Hopefully, it will be a one stop shop so people can go to a single source for the information. At the moment, some countries give the information and some don't, some collect it in one way and some in another."
The EMA had argued that circulating all the data it collects about adverse reactions to drugs could prove "misleading" or "unreliable" because many suspected cases turn out not to be linked with the drug in question.
But the ombudsman disagreed, saying the EMA should include warnings with the data to reduce the risk of misinterpretation. It added that the regulator had failed to provide Mr Grant valid and adequate grounds for its refusal to make the information available. "This constitutes an instance of maladministration," Mr Diamandouros said.
The EMA said it had launched an initiative to improve the transparency of its processes, due for implementation by the end of the year. A draft policy proposes that the general public should have access to "spontaneous reports for all types of medicines".
Roche said: "Since 1982, over 15 million patients have been treated with Roaccutane. Although there have been very rare reports of suicides and suicidal ideation in patients with acne being treated with the medicine, the fact is that severe acne can cause some sufferers to become depressed and can also affect their mood and self esteem.
"Although there is no proven causal link between Roaccutane and suicide, we stress through our patient information leaflet provided with every pack that patients must tell their doctors if they notice any change in mood or behaviour and give examples of the types of changes they should look out for."Reuse content