In 2021, the state became the first in the country to give its state health department the broad power to block acquisitions and mergers of hospitals, hospices and medical practices, an effort to counteract the consolidation that research shows is cutting competition and driving up costs nationwide.

Lawmakers said Oregon’s novel oversight power would stop multibillion-dollar deals from reducing care and increasing costs. State regulators got the authority to reject transactions or to add conditions and levy fines if companies disregarded them. The law was hailed as a national model.

Five years later, Oregon has not formally blocked a single transaction or issued any fines. While the new oversight is credited with leading to the withdrawal of two high-profile transactions — a merger of two Portland-area hospital systems and the acquisition of a nonprofit that provides Medicaid benefits to half a million Oregonians — some people who supported the law say it has not been nearly as effective as hoped.