Thousands of Australian credit-card holders paying for so-called "junk" - or essentially worthless - insurance could be eligible to join a potential class action against the big four banks.
The law firm Slater and Gordon is leading the investigation into the case, in which millions of dollars of such insurance was sold.
Solicitor Amanda Storey says she regularly hears from people who fear they have been taken advantage of, including bank customers who have purchased seemingly worthless credit insurance.
Ms Storey works with the Consumer Action Law Centre in Melbourne and regularly campaigns on the issue.
"I think they are sold inappropriately, and I think it's scandalous the banks have been able to keep selling these products for such a long time when they're on notice that so very few consumers can actually claim on them."
Consumer credit insurance is added on to protect customers if repayments on their cards, or other products, cannot be met because of death, illness or job loss.
But many consumers are actually ineligible to claim some or all of the benefits, making the insurance essentially worthless.
The law firm Slater and Gordon is investigating a potential class action against the major banks on behalf of what could be tens of thousands of customers.
Slater and Gordon class-actions senior associate Andrew Paull says many people are confused by the insurance.
"It's typically when you're applying for a credit card or for a personal loan. And that can be in the bank branch or on the phone. The transaction can happen very quickly, and some people are not even aware that they've purchased an insurance product. But that's the time it's sold."
The potential class action would capture a variety of groups.
They include people on Centrelink such as students and the unemployed, customers with pre-existing medical conditions, people over 65 years old, and casual and contract workers.
Last week, the Commonwealth Bank announced it would refund up to $16 million to customers who bought questionable add-on insurance policies.
It also withdrew those products from the market.
Mr Paull says the class action would be seeking a similar remedy.
"We will, similarly, be seeking refunds from other banks who've been selling this product inappropriately. I think the pressure is building on the banks generally. So, they enjoy a very privileged position in our society, and it's becoming clear that society expects them to behave a bit better than they have been doing."
The potential class action comes as a royal commission into the banks prepares to hear from witnesses for the first time today.
Financial Counselling Australia chief executive Fiona Guthrie says it is an important moment for Australia's banking industry.
"I'm quite optimistic that this could be a really, really good experience. It might be painful, about ripping the bandaid off,* but, in the long run, I think it will be good for the banks and it will be good for the community."
The royal commission will tackle several issues over the next fortnight, including residential mortgages and credit-card limit increases.
