An Ontario judge has acquitted all defendants in the tainted blood scandal, angering victims of the worst public health disaster in Canadian history.

Ontario Superior Court Justice Mary Lou Benotto delivered her verdict Monday afternoon in a Toronto courtroom, ending the 18-month long trial.

Former Canadian Red Cross chief Dr. Roger Perrault, three other doctors and the New Jersey-based Armour Pharmaceuticals Co. were all acquitted.

"There was no conduct that showed wanton and reckless disregard," said Benotto.

She then went on to say: "The conduct examined in detail over one and a half years confirms reasonable and responsible and professional actions and responses during this difficult time. The allegations of criminal conduct on the part of these men and this corporation were not only unsupported by the evidence, they were disproved."

Defence lawyer Eddie Greenspan, who represented Perrault, said the ruling has restored his client's reputation.

"Today's absolute vindication, and his complete exoneration, is something we've been expecting for the last 10 years," he told reporters outside the court building.

"But he's not a happy man. He's spent 10 years of his life trying to get his reputation back, although I've no doubt that this has done it."

More than 20,000 Canadians contracted HIV or hepatitis C from tainted blood products administered in the mid-1980s.

All defendants had pleaded not guilty to criminal negligence charges. Lawyers for three of the accused doctors had argued the Crown lacked a substantial amount of evidence to prove its case.

It was alleged the defendants were criminally negligent in the distribution of an Armour HIV-infected blood-clotting product between July 1986 and December 1987.

James Kreppner, a hemophiliac who contracted HIV through contaminated blood products, watched the trial closely, both as a lawyer and advocate for fellow victims.

"I'm not out for revenge but I want the truth told as well, and I think the initial inquiry into the blood system told the truth," he told reporters. "And I expected something to happen as a result of those facts."

Another victim, Mike McCarthy, was blunt in his reaction to Monday's verdict.

"It's a shock, the verdict, and I think every tainted blood victim is going to feel there is no closure here. We feel it's been a miscarriage of justice."

But in delivering her ruling, Benotto cautioned against continued blame for the scandal.

"The events were tragic. However, to assign blame where none exists is to compound the tragedy," she said.

The Globe and Mail journalist Andre Picard, who also followed the trial, wrote a book about the blood scandal called "The Gift of Death." Picard told CTV's Canada AM that the criminal trial is a small part of a much larger tragedy.

"It's important legally because it's the first case and it's important symbolically but it's not an indictment of the tainted blood tragedy, that's not possible to do in a court of law," Picard said Monday.

"We're looking at a very specific case, to make an example of people, I think, is a better way of putting it."

A second criminal trial for Perrault -- dealing more specifically with how the Canadian Red Cross and senior health officials failed to prevent the spread of disease through donated blood -- is set for Hamilton, Ont.

"They're both important cases, but I have to emphasize that you can't put tainted blood in a criminal context," Picard said.

The Canadian Red Cross is no longer involved in blood distribution. In 1998, that responsibility was transferred to Canadian Blood Services and Hema-Quebec.

In May 2006, the Canadian Red Cross apologized and pleaded guilty to violating the Food and Drug Regulation Act by distributing tainted blood products. The Crown withdrew charges of criminal negligence causing bodily harm and common nuisance against the charity in exchange for the guilty plea.

The Red Cross agreed to pay a $5,000 fine and allotted $1.5 million for a University of Ottawa scholarship fund and research project aimed at reducing medical errors.

As of 1997, the death toll for those who received tainted blood products was 3,000. It's unclear how many others have died since then.