For years, it was a mystery: Seemingly out of the blue, therapists would feel like they’d tripped some invisible wire and become a target of UnitedHealth Group.

A company representative with the Orwellian title “care advocate” would call and grill them about why they’d seen a patient twice a week or weekly for six months.

In case after case, United would refuse to cover care, leaving patients to pay out-of-pocket or go without it. The severity of their issues seemed not to matter.

Around 2016, government officials began to pry open United’s black box. They found that the nation’s largest health insurance conglomerate had been using algorithms to identify providers it determined were giving too much therapy and patients it believed were receiving too much; then, the company scrutinized their cases and cut off reimbursements.

By the end of 2021, United’s algorithm program had been deemed illegal in three states.

But that has not stopped the company from continuing to police mental health care with arbitrary thresholds and cost-driven targets, ProPublica found, after reviewing what is effectively the company’s internal playbook for limiting and cutting therapy expenses. The insurer’s strategies are still very much alive, putting countless patients at risk of losing mental health care.

Optum, its subsidiary that manages its mental health coverage, is taking aim at those who give or get “unwarranted” treatment, flagging patients who receive more than 30 sessions in eight months. The insurer estimates its “outlier management” strategy will contribute to savings of up to $52 million, according to company documents.