Insurance companies believe married people are better drivers – until death do they part. Then, a widow automatically becomes a higher risk, justifying a premium increase of up to 20 percent.

That’s the troubling finding of a Washington-based consumer group that surveyed insurers in 10 cities and found most levy a “widow’s penalty,” the result of disparate charges for married and single drivers. To continue to do so, insurers should provide proof that a marriage certificate makes for a responsible driver and that risk spikes after the death of a spouse.

The Consumer Federation of America obtained rates for a hypothetical driver in 10 cities, comparing the premium for a married woman and a widow, at both 30 and 50 years old. It found that four of six insurers – Geico, Farmers, Progressive and Liberty Mutual – charged the widow an average of 20 percent more than the married woman. Nationwide did in some cities; State Farm did not change its rates based on marital status.

In response to a report by the Pittsburgh Post-Gazette’s Tim Grant, the Pennsylvania Insurance Department will investigate and ask insurers that raise rates for widows and widowers to justify the increase or lower the rates. In the past, insurers have cited old studies to demonstrate correlation between marital status and risk, including one based on data collected in New Zealand in 1990, the CFA said.

A fair system, consumer advocates say, would consider only a person’s accident record, speeding tickets and the number of miles driven.

If married people are truly better drivers, and the bereaved worse, let’s see recent, definitive data. Otherwise, consumers should effect change by choosing insurers that don’t ask for their marital status.