Thousands of women are due to share hundreds of millions of dollars in compensation after Johnson & Johnson failed to overturn a landmark ruling finding it concealed the true extent of complications of damaging medical devices.
A Federal Court judge in 2019 found the pharmaceutical giant acted negligently and concealed the true extent of complications from the pelvic implants.
Hundreds of the synthetic implants eroded, extruded or caused infection without warning - leaving women in chronic pain and with damage to surrounding organs.
"Instructions for Use" brochures handed to surgeons were also found to have minimised harm and exaggerated the benefits of the devices.
Johnson & Johnson appealed the decision, alleging there were numerous legal errors including a reversal of the onus of proof, but the challenge was dismissed on Friday.
Brisbane woman Peta Bennett, who had tension-free vaginal tape implanted in 2004, said she broke into tears when she heard Friday's decision.
The ruling restored her faith in the court system but didn't change the fact day-to-day tasks such as going shopping with her granddaughter remained difficult.
"Every day is a struggle, to be honest," Ms Bennett said.
"She doesn't understand what's wrong with you, because I probably look fairly normal when I'm just trying to be happy."
The implant had robbed her of the ability to look ahead and plan a happy and fulfilling life.
"They should have never done what they did," she said.
The corporation had contended the judge ignored the critical question as to whether, having looked at the risk, warnings and nature of the implants, the devices' safety was not as people are entitled to expect.
Rebecca Jancauskas (left) from Shine Lawyers, Pelvic mesh victim Peta Bennett (centre) and her daughter Allison Welch (right) pictured during the conference. Source: AAP
"It is plain from Her Honour's reasons that she considered each of those matters," the Full Court of the Federal Court said on Friday.
The court could accept the devices proved to be effective for many women - "perhaps a majority" - to treat pelvic floor issues.
But the medical giant trumpeted the benefits while failing to properly warn that each device posed a risk of severe complications to any woman using them.
"The fact that the risk only eventuated in some women implanted with the devices, rather than all women, does not mean that the devices have the safety persons generally are entitled to expect," the appeal court said.
The court also dismissed suggestions the warnings to surgeons was adequate or that too little weight was given to the evidence of surgeons.
"The fact that the marketers considered disclosure undesirable indicates that the appellants themselves did not believe that pelvic surgeons knew about the pleaded complications," the court said.
The class actions practice leader for Shine Lawyers, which launched the case in 2012, said Johnson & Johnson had vigorously defended it matter at every opportunity.
"Now the court has comprehensively found that Johnson & Johnson are liable for the losses that these women have suffered," Rebecca Jancauskas said.
About 10,000 women have registered their interest in joining the class action, which Ms Jancauskas said made it the largest product liability class action in Australian history.
The court last year awarded the three lead litigants a total of $2.6 million in damages, paving the way for full payout in the hundreds of millions.
Exactly how many women will be included in any settlement remains unknown after the court on Friday said the previous description was too imprecise.
Johnson & Johnson said its subsidiary Ethicon empathised with all women who experienced medical complications and believed it had acted ethically and responsibly at all times.
"Ethicon is reviewing the Full Court decision announced today and will consider its options," a spokeswoman told AAP.
