Under landmark legal settlements reached in 2004 and 2005 between state regulators and UnumProvident Corp., one of the country’s largest disability insurers, the company was required to reopen hundreds of thousands of disability insurance claims that it had rejected.

But as Unum prepares to close the books on the claims-reopening process this year, the company says it will have reviewed fewer than 10% of the 290,000 claims eligible for a second chance, including 25,000 in California.

The company, now called Unum Group, said few cases were reviewed because most worker claimants chose not to reopen their cases, apparently accepting the company’s initial rejection.

But consumer advocates say workers’ belief that the claims-resolution process remains unfair has kept them from seeking a review. The accords, which involved regulators from California and several other states, were supposed to reform that process but have largely failed to do so, the advocates say.

As a result, legitimate claims from many policyholders with serious work-related injuries continue to be rejected, subjecting families to financial hardships and forcing some of those hurt to go back to work against the advice of their doctors, critics say.

Disability insurance is held by more than 50 million U.S. workers and represents a crucial safety net for middle-class families. Offered as a benefit by many employers, it usually replaces half or more of a worker’s income should he or she become disabled and unable to work.

Consumer advocates and many workers have long contended that, among other things, insurers use biased medical exams that deem someone fit to work even against the advice of treating physicians. And federal law doesn’t help, they say. In most cases, insurers are given wide latitude in determining whether to pay claims.

The settlements required Unum to change its medical review process by giving treating physicians’ opinions more weight, for example.

But the agreements failed to rein in the considerable power Unum and other insurers wield in handling claims, consumer advocates say.

Although state regulators hoped the settlements with Unum would entice other insurers to fall in line, there is no indication they did. When California insurance regulators tried to expand a key provision of the Unum settlement to other insurers, the industry sued and blocked the move.

Unum, which insures more than a quarter of the nation’s disability policies, says it is a changed company.

He said Unum paid the vast majority of disability claims, more than 90%, without incident.

But critics point out that even a small percentage of denied claims, especially if involving long-term benefits to highly paid executive-level workers, can save Unum millions of dollars.

Although agreeing with state regulators to change its medical review process, for example, Unum continued to defend its practices in courtrooms against individual claimants who had sued. In one case, Unum insisted that a man who had quintuple bypass surgery was fit to go back to his job at a stock brokerage firm, even though his doctors said the stress might kill him. In another, the company refused benefits to a man who had had multiple heart attacks.

In California, the company did agree to a third-party independent review of unresolved cases involving previously denied claims, but it refused to be bound by its findings.