The state Department of Insurance and the N.C. Rate Bureau, which represents 144 auto insurers, disagree on the premiums the companies should be able to charge beginning Oct. 1. That disagreement triggered the hearing that begins today.

What's at stake: The Rate Bureau wants to raise rates an average of 13 percent -- the largest increase it has sought since 1994. The Insurance Department will present two witnesses to recommend rates be cut between 17 percent and 20 percent, said department spokeswoman Chrissy Pearson.

The state estimates the increase sought by the Rate Bureau averages $83 per vehicle.

The rates at issue are the maximum increase insurers can charge North Carolina drivers. The amount would vary in different regions and with different types of coverage. And thanks to competition, insurers charge many drivers less than the maximum rate.

The process: Opening statements. Witnesses. Cross-examinations. It's similar to a civil trial. So the wheels move slowly. Closing arguments are tentatively set for July 29.

The decider: Insurance Commissioner Jim Long presides and will rule on a rate. To be sure, Long's department is a party in the proceedings. But Long has been removed from the process up until now; his staff has been carrying the ball.

The hearing will be the last hurrah for Long, commissioner since 1985. He isn't seeking re-election.

The background: The industry last proposed a rate increase in 2006. The last rate hearing was in 2005.

The issues: The Rate Bureau cites the rising medical costs and a slowdown in the declining rate of accidents. The state contends the Rate Bureau provided incomplete data that skews the numbers; the bureau insists that's not the case.

Past claims data are used to predict the future. A disagreement on an item such as the future inflation rate can have a big impact.

What's next: A settlement is still possible. Any decision by Long can be appealed to the courts. If the Rate Bureau appeals, it can implement an interim rate hike, but the difference between the rate it sets and the rate ordered by Long would be escrowed. If the Rate Bureau loses its appeal, it must refund the difference, plus interest.

When and where: 10 a.m. today in the third-floor hearing room at the state Insurance Department, 430 N. Salisbury St. It's open to the public, but be advised that the issues are technical and laden with numbers. For more information, contact the department at 733-5238.

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