A public inquiry into the infection of patients with hepatitis C has been ruled out by Health Minister Andy Kerr.
Mr Kerr says important lessons have been learnt since the 1980s
He said an inquiry was unlikely to uncover any new relevant evidence or information and would bring little benefit to the patients involved.
A Holyrood committee had asked for a judicial inquiry into how thousands of people contracted the virus from blood products in the 1970s and 80s.
One patient said those who had been infected may now take legal action.
In response to the Holyrood health committee's request in April, Mr Kerr said: "A full judicial inquiry would be a major and time-consuming exercise which would depend on the recollections of witnesses about events which took place 20 or more years ago.
"This would make it difficult to construct a clear and detailed picture of what took place."
In a letter to the MSPs, Mr Kerr said the transmission of the virus through the blood supply had taken place before testing was introduced in 1991 and at a time when there was limited scientific and medical knowledge about the condition.
The minister pointed to the decision to set up a payment scheme for victims UK-wide, and a "look-back" exercise which had been decided on by UK ministers before devolution.
"Testing and counselling are still available for anyone who considers they are at risk as a result of a transfusion before 1991", he added.
Mr Kerr told the committee: "There is already substantial published evidence on how the understanding of hepatitis C and its implications for blood donation, blood products and blood transfusion developed over time.
"I do not believe a public inquiry would either uncover any new evidence or information that is relevant to the causes of the infection of NHS patients through blood and blood products, or lead to significant lessons for the future.
"It would be a diversion of effort from delivering and improving health services today."
Campaigner Andrew Gunn, of the Scottish Haemophilia Group Forum, branded Mr Kerr's announcement a "sham".
"The system is rigged against us - that's why they won't give us legal aid after years of campaigning," he said.
"The truth is too politically volatile. It would leave senior civil servants, politicians and pharmaceutical companies facing billions of pounds of compensation.
"The truth is they knew the dangers, but just got on with it."
Chairman of the Scottish Haemophilia Group Forum, Philip Dolan, said the group would continue to pursue the issue.
A patient, who wished to remain anonymous, was diagnosed with the virus a year and a half ago, after becoming infected in the 1980s.
The woman, who passed hepatitis C onto her partner, said she and other sufferers were planning to go ahead with legal action now that a public inquiry had been ruled out.
Health committee convener Roseanna Cunningham of the SNP expressed her disappointment at the minister's decision.
She said: "I don't think it does Scotland any good to have real concerns such as these ignored by the executive."
SSP health spokesperson Carolyn Leckie said a number of documents from the various health and legal departments involved had never been released.
She claimed there should have been an independent judgement on the information.