America’s largest personal lines insurer Allstate ranks as the worst US insurer for consumers, according to a new report that details thousands of legal documents uncovered from litigation, testimony and complaints filed with state insurance departments.

The report, produced by the Washington-based American Association of Justice (AAJ), shows a distinct pattern of insurance industry greed among 10 companies that refuse to pay legitimate claims, employ rough tactics against policyholders, reward executives with extravagant salaries and raise premiums while making excessive profits.

The report says Allstate set the standard for insurance company greed, conspiring with consulting giant McKinsey & Co in the mid-1990s to place profits over policyholders’ interests.

“While Allstate publicly touts its ‘good hands’ approach, it has instead privately instructed its agents to employ a ‘boxing gloves’ strategy against its policyholders,” AAJ CEO Jon Haber said.

But Allstate says the allegations are “without merit”, and released the 150,000 pages of confidential documents to prove it has nothing to hide.

“Public criticisms by people with a vested interest in creating an inaccurate picture of the company’s claim practices have been based unfairly on snippets from the documents taken out of context,” the company said in a statement.

Disability insurer Unum ranked as the second-worst insurer, with AIG – which the AAJ described as “the new Enron” – coming in third.