The auto insurer GEICO Corp, a unit of Warren Buffett’s Berkshire Hathaway Inc, must face a proposed class action claiming it overcharged policyholders as the coronavirus pandemic led to less driving and fewer accidents, a judge has ruled.

In a decision on Thursday, U.S. District Judge Sharon Johnson Coleman in Chicago said Illinois drivers may try to prove GEICO violated a state consumer fraud law by unfairly and deceptively marketing its “GEICO Giveback” discount program. She dismissed breach of contract and unjust enrichment claims.

Neither GEICO nor its lawyers immediately responded to requests for comment on Friday. Lawyers for the plaintiffs did not immediately respond to similar requests.

GEICO had last April offered policyholders $2.5 billion of credits, including 15 percent on renewals from April to October, averaging about $150 per policy.

But policyholders led by Briana Siegal said this induced them to renew and pay excessive premiums rather than shop around, as stay-at-home orders and closures of businesses and schools resulted in less time on the road.

Siegal also said GEICO’s credits compared unfavorably with refunds offered by other insurers.

She cited a report by the Consumer Federation of America and Center for Economic Justice awarding GEICO’s program a “D-minus,” below the “A” and “B” grades given to State Farm and Allstate Corp, which offered refunds.

Without ruling on the merits, Coleman said the plaintiffs adequately alleged that GEICO misled them into thinking it was passing on all its savings from reduced driving, and failed to disclose that its premiums were “not based on an accurate assessment of risk during COVID-19.”

GEICO’s “loss ratio,” or percentage of premiums paid to cover claims, fell to 74.1 percent in 2020 from 81.3 percent a year earlier, and was the lowest since 2007.

Berkshire, based in Omaha, Neb., has owned all of GEICO since 1996. GEICO is based in Chevy Chase, Maryland.

The case is Siegal v GEICO Casualty Co et al, U.S. District Court, Northern District of Illinois, No. 20-04306.