They argue that when a consumer's credit information results in the consumer receiving a higher rate, insurers should send out "adverse action notices" required under FCRA. They also contend the insurers acted in willful disregard of the FCRA in not doing so.

FCRA adverse action notices are sent to consumers by banks, landlords and others when a consumer's credit report has caused them to be denied for a loan or a lease, for example, or even if a consumer is required to have a higher than usual down payment or deposit due to their credit score, the Delaware insurance department said in a statement.

Mr. Denn and the twelve other insurance commissioners told the court that they were filing their brief to "further their collective mission of protecting consumers by supporting interpretations of the FCRA that puts valuable information in the hands of consumers; provides appropriate incentives for insurance companies that use consumer credit information to adopt procedures that assure compliance with the law; and holds insurance companies accountable when they adopt policies that recklessly disregard consumer rights in contravention of the FCRA."

The brief urges the court to uphold the decisions of the 9th U.S. Circuit Court of Appeals in the Safeco and GEICO cases that the companies willfully disregarded the FCRA by not sending adverse action notices to some consumers.

"I will continue to support legislation that would prohibit the use of credit scoring in auto and homeowners insurance, but I also thought it important to weigh in on this case," said Mr. Denn in a statement.

"As long as our law allows insurance companies to use credit scoring, consumers deserve to know when something in their credit score has resulted in them getting higher rates," he added.

The other states joining in the brief include Arkansas, California, Georgia, Iowa, Kansas, Michigan, Montana, New Mexico, North Dakota, Oklahoma, Utah and Washington.

Michael Vild, deputy insurance commissioner for the Delaware Department of Insurance, said the agency advised other state regulators of its planned brief through the National Association of Insurance Commissioners and invited them to join their filing. He said the department was quite pleased with the level of participation given the brief period of time.

Last year, he noted, Delaware tried to pass legislation banning the use of credit scoring in underwriting. A compromise that was eventually struck died with the legislative session. But he predicted some bill regulating the practice will reappear this session.

Oral arguments in the case are scheduled for Jan. 16.