The Medical Board of California has launched investigations into doctors who prescribed opioids to patients who, perhaps months or years later, fatally overdosed, according to a report by Kaiser Health News.

The effort, dubbed “the Death Certificate Project,” has sparked a conflict with physicians in California and beyond, in part because the doctors being investigated did not necessarily write the prescriptions leading to a death. The project is one of a kind nationally, although a much more limited program is operated by North Carolina’s board.

So far, the board has launched investigations into the practices of about 450 physicians and referred the names of 72 nurse practitioners, physician assistants and osteopathic physicians to their respective licensing boards. To date, the regulators have formally accused at least 23 doctors of negligent prescribing, and more accusations are expected.

Using terms such as “witch hunt” and “inquisition,” many doctors said the project is leading them or their peers to refuse patients’ requests for painkiller prescriptions – no matter how well documented the need – out of fear their practices will come under disciplinary review.

The project, first reported by MedPage Today, has struck a nerve among medical associations. Dr. Barbara McAneny, the American Medical Association president and an Albuquerque, N.M., oncologist whose cancer patients sometimes need treatment for acute pain, called the project “terrifying.” She said “it will only discourage doctors from taking care of patients with pain.”

The influential California Health Care Foundation also has pushed back against the project, saying it could harm patients.

Unusually aggressive for the board, the program is a reaction to the by now well-known phenomenon of physicians overprescribing opioids. Nationally, a host of policy changes and educational efforts have driven down the rate of opioid prescriptions in recent years.

The goal of California’s program, quietly launched four years ago, is not necessarily to link a doctor’s specific prescription to a specific patient’s death – although many of the cases do – but to find doctors whose patterns of prescribing are so dangerous they may lead to patients’ ultimately fatal addictions.

Kimberly Kirchmeyer, executive director of the Medical Board of California, defended the project. She said the effort has found patterns of “gross negligence,” incompetence and excessive prescribing.

“I understand their frustrations,” she said of the complaining doctors, “but we do have to continue our role with consumer protection.” She noted that part of the point of the project is to educate doctors and, through probation requirements, change the behavior of those who prescribe excessively. “That’s education that could potentially save patients in the future,” said Kirchmeyer, whose agency licenses some 141,000 doctors.

Some consumer groups consider the board’s bold effort to find overprescribing doctors not aggressive enough.

“It’s long overdue,” said Carmen Balber, executive director of the nonprofit Consumer Watchdog. The board should investigate opioid-related deaths that occurred more recently, she said: “They need to get their act together and speed things up.”

McAneny, of the AMA, noted that prescribing practices now deemed unacceptable came out of public policies years ago that “compelled doctors to treat pain more aggressively for the comfort of our patients.” Also, payers have measured quality of care by whether their patients answered surveys about whether their pain was well-controlled.

Similarly, Dr. David Aizuss, a Los Angeles ophthalmologist who is president of the California Medical Association, said state and federal guidelines that took effect in 2014 and 2016 impose much more stringent prescribing precautions than “what was going on six or seven years ago.”

The crackdown on doctors has created fear, said Dr. Robert Wailes, a pain medicine specialist in Encinitas and chair of the California Medical Association’s Board of Trustees. “What we’re finding is that more and more primary care doctors are afraid to prescribe and more of those patients are showing up on our doorsteps,” he said.

Officially, the CMA stops short of saying the medical board should stop the project, perhaps to avoid any perception that the association condones overprescribing. But it has asked the board to hire an independent reviewer to assess the criteria the board is using to decide which physicians to investigate, and whether physicians in certain specialties or regions of the state are being targeted more than others.