Victims and families have won a ruling allowing them to launch a High Court group action seeking damages over contaminated blood products.
A High Court official said it was "appropriate" to immediately issue a group litigation order allowing a potential 500 claimants - surviving victims of contamination and the families of the deceased - to join together to claim compensation.
The official, Senior Master Fontaine, made the order despite opposition from lawyers acting for the Department of Health who argued the application was "premature".
The case concerns imported blood-clotting products derived from blood plasma which caused haemophiliacs and others to be infected with HIV and hepatitis in the 1970s and 80s and has so far led to the deaths of at least 2,400 NHS patients.
This summer, a widow and campaigner, former Hartlepool woman, Carol Grayson, welcomed a new inquiry into the scandal.
Carol, 57, has spent more than a decade uncovering evidence and campaigning. She lost her haemophiliac husband Peter Longstaff in 2005 after he contracted HIV and hepatitis C from contaminated blood.
She wrote an MA thesis at Sunderland University on the global blood trade, which won an award, and which traced infected donors to Arkansas prisons.
Reacting to the Prime Minister's announcement of an inquiry in July, she said: "I'm pleased that an inquiry has been announced and I'm grateful to politicians that have stuck with us for so long.
"This cover-up has been going on for almost three decades and I've been largely ignored.
"I would like the inquiry to cover all the evidence that we've already covered, which includes complaints we've submitted to official bodies, including the General Medical Council (GMC) and the Government."
Carol said she was able to trace her husband's treatment batch numbers back to Arkansas State Penitentiary, where prisoners were being paid to give blood samples.
The claimants allege that the Department of Health failed in its duty to take reasonable care to prevent injury or loss to NHS patients when contaminated blood products manufactured from blood donated "from unsafe sources", mainly in the USA, were imported into the UK, causing a large number of haemophiliacs to be infected with hepatitis C and HIV.
In the US, prisoners and people who were addicted to drugs, were among those paid to give their blood to meet the rising demand for commercial blood products.
Their contaminated donations were mixed in with those of others.
Master Fontaine was told more than 4,500 people contracted hepatitis C and/or HIV in the 1970s and 80s.