An imposing new obstacle is getting in the way of the nation’s personal-injury lawsuits. It has nothing to do with the merits of the cases, or how the courts are operating. The obstacle is Medicare, the federal health insurer for the elderly. Lawyers say the program is disrupting a countless number of their settlements.

Court papers in Connecticut describe one example: After a minor is hurt in a traffic accident, his family agreed to a settlement of $7,500 with the other party’s insurer, but the settlement broke down when the insurer, United Services Automobile Association, said it needed to run the minor’s case by Medicare. Minors aren’t eligible for Medicare, but the insurer said it had no choice under federal law.