Suspicions that vaccine trials had taken place on vulnerable Irish children -- many of whom were in state care -- first surfaced in the early 1990s.
As the current decade dawned, former residents of children's homes began to publicly raise concerns that they had been the subject of experimental trials.
However, it was not until 1997 that the State gave an assurance that it would formally inquire into the issue.
Brian Cowen, who was then Health Minister, directed the chief medical officer at the Department of Health, Dr James Kiely, to investigate the allegations.
In 2000, a report -- entitled the "Report On Three Clinical Trials Involving Babies And Children In Institutional Settings, 1960/61, 1970 and 1973" -- was finally drawn up.
The document found that 211 children had been administered vaccines during three separate vaccine trials conducted on behalf of a drugs company, The Wellcome Foundation.
More than 123 of these infants and toddlers were residents in children's homes in Dublin, Cork and the midlands when the trials took place in the 1960s and 1970s.
Trial one involved 58 children in five children's homes in Dublin, Cork, Westmeath and Meath. The trial investigated what would happen if four vaccines -- diphtheria, pertussis (also known as whooping cough), tetanus and polio -- were combined in one overall four-in-one shot.
The trial was published in the 'British Medical Journal' in 1962. The final paragraph of it read: "We are indebted to the medical officers in charge of the children's homes. . . for permission to carry out this investigation on infants under their care."
Trial two, which was conducted during the summer of 1970, saw 35 children administered with the intra-nasal rubella vaccine.
It involved children from St Anne's Industrial School in Booterstown, Co Dublin, and children living in the Killucan area of Westmeath.
Published in the 'Cambridge Journal of Hygiene' in 1971, the trial attempted to find out if German measles vaccine, administered intranasally, could spread to susceptible contacts.
Both trials were carried out by Professor Irene Hillery and Professor Patrick Meenan, from the department of Medical Microbiology in University College Dublin, and other doctors.
The final trial involved 53 children from institutional homes. The homes were: St Patrick's Home, Madonna House, Cottage Home, Bird's Nest and Boheennaburna. A further 65 children living at home in Dublin also took part.
The purpose of the trial was to compare commercially available batches of the three-in-one vaccine, Trivax and Trivax AD, with that of a modified vaccine prepared for the trial.
Dr Kiely's report said the decision to conduct such clinical trials was acceptable, given the diseases that the vaccines sought to counter.
But, crucially, he insisted the lack of documentation available meant it had not been possible to confirm if consent had been given by the parents or guardians of the children involved or what arrangements were arrived at with managers of the homes.
He added that this lack of information also meant he could not confirm if the Therapeutic Substances Act 1932 had been complied with in relation to the licensing of the trials.
The damning document was laid before the Houses of the Oireachtas on November 7, 2000.
On November 9, the then Health Minister Micheal Martin told the Dail an important part of the probe was to establish if the State had fulfilled its obligations to children in its care.
But he admitted that the report was incomplete.
"It raises as many questions as it answers. Some of those questions go to the heart of our attitudes to children and their rights," he said at the time
"The report is incomplete because in some areas, the most rigorous interrogation of the system failed to produce documentary records of the trials."
Mr Martin said the Government had no evidence that any child had contracted a serious illness as a result of the trials.
But he branded the lack of documentation "puzzling" and insisted that the report had to be the "beginning and not the end" of the matter.
The minister referred the report of the investigation to the Commission to Inquire into Child Abuse -- known then as the Laffoy Commission.
A government order was subsequently made on June 19, 2001 to provide the commission with the powers to create a separate module to formally investigate the issues involved.
The 'Vaccines Module' initially convened a public sitting on January 23, 2002, to outline its terms of reference. It then began investigating the trials.
It obtained documents from GlaxoSmithKline, the successor of Wellcome, which allowed it to definitively identify the homes and people involved in the trials.
Investigators received so much information relating to trial one that they were able to identify the children given the 'four-in-one' vaccine.
It also conducted private interviews with witnesses to get a more accurate picture.
But just before the start of public hearings into the first trials, which were due to begin on June 17, 2003, the work of the commission was dealt a severe blow when the Supreme Court ruled that Prof Meenan did not have to give evidence.
Prof Meenan had appealed a High Court order requiring him to comply with the commission's direction to give evidence about his involvement in the trial.
The inquiry received a further setback when the Government's order directing the Laffoy Commission probe was held to be invalid by the High Court in November 2003.
Mr Justice Aindrias O Caoimh gave his decision in a challenge brought by Prof Hillery. However, he ruled that other machinery could exist for an appropriate inquiry.
On November 25, 2003, an undertaking was given to the High Court by the commission that it would not conduct any hearings in relation to matters within the ambit of the order.
It had been hoped that the Government would appeal this decision. But on November 2006, Health Minister Mary Harney ordered the vaccine module to be closed down.
Now, some of the victims have been left with no alternative but to seek redress in a US court after Ms Harney again firmly ruled out any further inquiries into existing or new allegations.
The victims' basic requests appear to be far from unreasonable; an apology for what was done to them; full medical screening to see if they have suffered any damaging long-term effects from the trials; and psychiatric counselling to help them get over their ordeal.
But even this, it appears, is beyond the capacity or willingness of the State to deliver.