ACC is to reassess claims for surgical mesh injuries it previously declined, as well as consider fresh claims it receives.
Nearly 400 people could have their cases reassessed under the guidelines, which were developed based on the latest medical evidence and understanding of mesh injuries.
ACC's announcement arose from a restorative justice process last year, during which 600 people injured by surgical mesh shared their stories through 32 online forums or an online database.
Campaigner Patricia Sullivan, who co-founded the support group Mesh Down Under, said the change was good news for claimants.
She said as of September, 377 claims dating back to 2005 - most of them women - were declined. For those people, ACC is the only avenue for having their medical costs met, she said.
Another problem for mesh complications is pain - a symptom ACC did not consider until now.
"It's basically a chronic inflammation occurs at the site of the mesh and that can mean that the mesh can contract and it gets stiff and it gets very painful.
"So people can have abdominal pain, pain at the site of the surgery, internal pain, pain on intercourse, neuropathic [pain], terrible. It's like the worst toothache you could ever imagine," she said.
Charlotte Kerr is a solicitor at John Miller Law and has been involved in several cases involving mesh claimants.
She said there were a number of hurdles clients had to overcome before ACC would accept the claim - that is before compensation could even be considered.
Under ACC's treatment injury criteria, a claimant must show they suffered a physical injury as a result of treatment. For mesh, physical harm includes damage to the nerve, which must be seen and the damaged nerve must be named.
"It's incredibly difficult to identify the damaged nerve and know precisely the mechanism of injury. Our diagnostic tools, and perhaps our medical science, might not be able to identify microscopic damage to nerves," Kerr said.
She said it was then up to the ACC claimant, already suffering from their injuries and perhaps unable to work, to engage doctors and pay for diagnostic tests to prove the precise nature and location of that damage, which is incredibly onerous for that claimant.
Urological Society of Australia and New Zealand president Stephen Mark operates on patients who have had complications from mesh where it involves the urinary tract.
He welcomed ACC's announcement, saying expanding the claim criteria would help improve the outcomes for patients who had complications from mesh - including the criteria for pain.
"The new ACC document clarifies where ACC would cover pain, where there was not pain present prior to surgery and no previous pain problems and the pain was directly linked to the site and the location of the mesh, with some objective evidence there was a problem," he said.
In a statement, ACC said under the new guidelines, where there is clear evidence of mesh erosion or extrusion, specific nerve damage, surgical error or infection caused by treatment, it is now likely to accept the claim.
While it has updated and released new guidelines for gynaecology claims, it is yet to release new guidelines for those who have suffered complications from hernia treatment, which mostly involves men.
Sullivan was suspicious of that decision.
"We want to know, when did ACC start writing these hernia guidelines and why are they assessing all mesh claims if the hernia guidelines aren't completed? When will these guidelines be published and who will be the hernia specialist external assessors looking at these hernia claims?" she asked.
She also wanted more information about what independent oversight there would be of the reassessment process and what, if any, evaluations would be published.
She said that for a group that had fought for so long, transparency was important and they did not want it to be a box ticking exercise.
"We are wanting outcomes and the only way we will know if these outcomes are robust is if we have a report that evaluates those outcomes and if we know that there has been independent oversight of this process," she said.
ACC said it was continuing to work with external medical experts on its guidelines for hernia mesh claims.
"There is no time limit for clients to take up this opportunity, and we will be monitoring requests and providing regular updates on the number of requests we're receiving and the outcome of those reassessments," ACC chief customer officer Emma Powell.
"As that progresses, we will consider the appropriate time to collate a report on the outcomes of this process. This regular reporting will ensure the process is transparent."
Sullivan expected more people to come forward as a result of today's announcement.
ACC said those wanting to have a mesh claim considered or file a new claim should ring its reassessment team or contact a GP or medical specialist.