More than 4,000 people were infected with Hep C before effective screening
Ministers have been given a deadline of a month to arrange an inquiry into the deaths of two people from Hepatitis C contracted through NHS blood products.
Relatives went to court to try to force the authorities to hold an inquiry into how Eileen O'Hara and Rev David Black contracted the virus while in NHS care.
After a judge ruled in favour of the families early last year, the Scottish Government promised a public inquiry.
However, eight months later, no date has been set.
Ministers had appointed judge Lady Cosgrove to chair the inquiry but she withdrew for personal reasons.
A Scottish Government spokesman said a replacement was expected to be appointed soon.
Mrs O'Hara and Mr Black died in 2003 after contracting Hepatitis C through blood transfusions or blood products supplied by the NHS.
Last February, Court of Session judge Lord Mackay ruled that their relatives had the right to expect a reasonably prompt inquiry into their deaths.
He said: "Since the deaths of Mrs O'Hara and Mr Black, both the lord advocate and the Scottish ministers have acted in a manner incompatible with the European Convention of Human Rights of the deceased."
Lord Mackay quoted article two of the convention, which states that "everyone's right to life shall be protected by law".
He quashed the lord advocate's decision not to hold Fatal Accident Inquiries into the deaths and also referred to ministers' refusal at the time to hold a full public inquiry into the general issue of infections through NHS blood products.
After this ruling, Health Secretary Nicola Sturgeon said she would honour an SNP manifesto promise to hold a public inquiry into how NHS patients were infected during the 1970s and 1980s.
A Scottish Government spokeswoman said: "We have received and are considering Lord MacKay's opinion.
"We are keen that the public inquiry should begin as soon as possible. However the withdrawal of the original chairman, inevitably, resulted in some delay.
"Ministers do not want any further delay and we expect to announce the new chairman imminently.
"In the meantime, preparatory work has continued - a fully-staffed inquiry team is in place and the draft terms of reference have been agreed between ministers and the incoming chairman."
However, in a supplementary opinion issued on Wednesday, Lord Mackay said he was giving the Scottish Government and Lord Advocate Elish Angiolini four to five weeks to comply with his original ruling and set up the inquiry.
Liberal Democrat health spokesperson Ross Finnie said: "The Health Secretary has failed to give any explanation as to why having appointed a judge, she has failed to appoint a replacement and therefore failed to meet the requirements of court.
"It would be unacceptable for the government to be in contempt of court on a matter of this kind. "
Mrs O'Hara and Mr Black were among more than 4,000 people who became infected with the virus during the 1980s, before effective screening.
The Scottish National Blood Transfusion Service did not introduce any Hep C screening test for blood donations until 1991.