California joined about a half-dozen states this month in banning the use of a person’s gender when assessing risk factors for car insurance, a change that could potentially alter rates for scores of drivers across the state.

The state, which is the country’s most populous, requires insurers to prioritize criteria like drivers’ safety records and years of experience behind the wheel when setting auto rates, but it also allows them to weigh other factors, like marital status. Gender had been among the optional criteria until the beginning of this year, when a new regulation went into effect prohibiting the practice.

In announcing the change, the departing state insurance commissioner, Dave Jones, said the new regulations “ensure that auto insurance rates are based on factors within a driver’s control, rather than personal characteristics over which drivers have no control.”

Mr. Jones’s term as commissioner ended in early January, and the new regulation was one of his final acts. The state’s Insurance Department, in explaining its reasoning for the change, noted that the industry had inconsistently — and perhaps unfairly — applied gender weighting in pricing.