Motor vehicle lawsuits in the US have risen sharply over the past decade, contributing to auto liability costs affecting premiums, the Insurance Information Institute says. 

An analysis by Triple-I and the Casualty Actuarial Society (CAS) finds motor tort filings growth outpaced broader federal civil court system changes from 2015 to 2024. 

It estimates the increase in motor litigation at $US43.84 billion ($63 billion), accounting for 25.3% to 30.5% of the $US143.6 billion ($206.4 billion) to $US173.1 billion ($248.7 billion) in rising inflation previously estimated for auto liability insurance for the period. 

“The data show a growing disconnect between motor vehicle tort litigation and underlying claims frequency,” Triple-I CEO Sean Kevelighan said. “The continued growth in litigation is another indication of how legal system abuse is adding to auto liability costs, ultimately affecting premiums.” 

The new research examines motor vehicle tort cases in federal and state civil courts. 

Other findings included that federal motor vehicle tort filings reached their highest level in three decades in 2024. 

The average amount awarded in federal motor vehicle tort judgments in favour of plaintiffs increased from $US377,000 ($541,745) during 1995-2004 to $681,000 ($978,590) for 2015-2024. 

CAS vice president research and practice advancement Morgan Bugbee says the data suggests liability loss trends may not be fully explained by claim frequency. 

“Changes in litigation activity, amounts demanded or awarded, and claim severity also contribute to insurance losses,” he said. “Comprehensive and consistent court data would help actuaries, researchers and policymakers assess these relationships more precisely.”