SACRAMENTO, Calif. (AP) — A lawsuit over high health bills filed on behalf of more than 3 million employers and people is seeking as much as $1.2 billion from one of Northern California’s largest health systems.

Plaintiffs in the antitrust class-action trial getting underway Thursday allege that Sutter Health abused its market power and “caused enormous adverse economic impacts” by discouraging patients from using lower-cost insurance and lower-cost hospitals.

Sutter Health two years ago paid different plaintiffs $575 million to settle similar claims that it used anti-competitive practices to artificially increase patients costs. Sutter says it didn't violate antitrust laws, and its volume discounts in fact lowered prices.