(Reuters) - Geico, the car insurer owned by Warren Buffett's Berkshire Hathaway ( BRK/A ), will not face class-action claims as it defends against a lawsuit alleging it overcharged policyholders early in the COVID-19 pandemic, a federal judge ruled on Tuesday.

U.S. District Judge Sharon Johnson Coleman in Chicago said policyholders in Illinois could not sue as a group because questions about calculating damages for individual drivers would "inevitably overwhelm" questions common to the proposed class.

She also found no "common injury" from Geico's statements that it created its "Geico Giveback" program because "shelter in place laws have reduced driving" and it wanted to start "passing these savings" to customers.

Class actions can let plaintiffs pursue greater recoveries at less cost than if they sued individually.

The case was brought by Illinois purchasers of Geico car, motorcycle or RV insurance since March 21, 2020, including those who visited the "What if I'm driving less?" or "Why are we doing this?" pages on Geico's website.

Geico in April 2020 offered policyholders $2.5 billion of credits, including 15% on renewals.

The plaintiffs said Geico should have joined rival insurers such as State Farm and Allstate by offering refunds as driving accidents declined.

They said Geico ended up charging "unconscionably excessive" premiums that violated Illinois consumer protection laws.

The plaintiffs' lawyers did not immediately respond to requests for comment. Lawyers for Geico did not immediately respond to similar requests.

Less driving during the pandemic contributed to Geico's "loss ratio," or percentage of premiums paid to cover claims, falling in 2020 to a 13-year low.

The insurer later suffered six consecutive quarters of underwriting losses, but has since rebounded by tightening standards and reducing policies in force. Geico earned $3.64 billion before taxes from underwriting in 2023.

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

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