Prior to 2008, the Division of Insurance set auto insurance rates in Massachusetts. After reforms were passed that year, the state instituted a form of prior approval called "managed competition".

Ms. Coakley noted that her proposed protections prohibit certain unfair and deceptive conduct in the sale of auto insurance, including prohibiting "discriminatory rating and underwriting factors," requiring "insurance rating practices to be fair and transparent," and preventing "misleading advertisements."

Insurer associations have claimed that consumers have fared better under managed competition than under the previous system, and that the proposed regulations are unnecessary.

They said Ms. Coakley has been opposed to the state's auto insurance reforms since before they were enacted.

Now, as the hearings take place, insurers are wondering whether Ms. Coakley has the authority to move forward with her regulations, a job they said belongs to the Division of Insurance.

Paul Tetrault, Northeast state affairs manager for the National Association of Mutual Insurance Companies said it is "highly questionable" whether the attorney general has such authority, and he noted the proposals conflict with existing regulations.

Frank O'Brien, vice president and Northeast regional manager for the Property Casualty Insurers Association of America (PCI), said the regulations represent a usurpation of the state insurance commissioner's authority to regulate insurance in the commonwealth.

He noted that if the regulations are implemented, litigation challenging them could ensue. Asked if PCI would file suit to block the regulations, Mr. O'Brien said the association plans "to keep all of our options open," adding that PCI is "very much opposed to" the proposed regulations.

Barbara Anthony, undersecretary of the Office of Consumer Affairs and Business Regulation, which houses the Division of Insurance, said the attorney general does, in fact, have the legal authority to promulgate regulations on a range of consumer protection issues.

Regarding the division's position on the regulations themselves, Ms. Anthony said, "We are taking a careful look at them and have not yet concluded our review."

She did note the benefits of the state's managed competition system, citing $270 million in savings to consumers in the first year, and increased capacity in Massachusetts.

She added that the division looks forward to working with Ms. Coakley to see what additional consumer protections can be added to "what is already a consumer-friendly market."