In a ruling that is causing a stir in Minnesota’s medical and legal communities, the state Supreme Court has said that a doctor can be sued for malpractice even in the absence of a traditional physician-patient relationship.

Medical groups say the opinion could subject physicians to more lawsuits, even in cases when they are simply giving informal advice to colleagues. The expansion of liability, they say, could also increase malpractice insurance premiums and have a chilling effect on consultations.

The court said its decision was aimed at doctors whose decisions have consequences. It arises from a case on the Iron Range, when a hospital doctor allegedly refused to admit a patient who was being treated by a nurse practitioner. The doctor did not see the patient and based his decision on a 10-minute telephone conversation, the details of which are in dispute.

The patient died three days later.

Both the district court and the appeals court dismissed the original lawsuit, filed by the patient’s family in 2016, because the doctor was not directly treating the patient. But the Supreme Court, in a decision last month, said the lower courts erred and had ignored precedents going back 100 years.

“We have never held that such a relationship is necessary to maintain a malpractice action under Minnesota law,” Justice David Lillehaug wrote for the 5-2 majority.

But the physician-patient relationship requirement was so commonly assumed that many reference books and journal articles cited it unquestioningly, said Thaddeus Pope, director of the Health Law Institute at Mitchell Hamline School of Law in St. Paul.

“It was surprising, and I think that it is important to note that they were very clear that they were not making [a] new law,” Pope said.

New law or not, the language of the opinion has medical groups and legal analysts asking who might be affected.

Could a primary care doctor, for example, be sued for failing to diagnose a patient’s infectious disease, allowing it to sicken someone else? That’s one of the scenarios the Minnesota Medical Association (MMA) posed in a bulletin sent to its members.

“It seems to be changing the conventional wisdom around when liability exists,” said Janet Silversmith, chief executive of the doctors’ organization. “That is why this ruling has caused the ripples that it has.”

Pope pointed to another possibility — doctors known as independent medical examiners, who conduct fitness exams for insurance companies and employers.

“They are not your doctor. They are examining you for somebody else,” he said. “Those clinicians … always thought that they had no exposure to medical liability because they are not in a treatment relationship with the patient.”

Legal scholars said that, with the opinion just a month old, its consequences will unfold as attorneys and judges cite it in malpractice cases going forward.

The underlying suit will head back to trial in St. Louis County District Court.

The case originated with a patient named Susan Warren, 54, who went to the Essentia Health Clinic in Hibbing in August 2014, complaining of abdominal pain, fever, chills and other symptoms. After getting test results, a nurse practitioner at the clinic called the local hospital, Fairview Range Medical Center, and asked to have Warren admitted, according to court documents.

Providers at the Essentia clinic did not have hospital admitting privileges, and they typically talked with a Fairview staff doctor, known as a hospitalist, who made the decision.

In this case, hospitalist Dr. Richard Dinter did not authorize an admission. According to court records, the nurse and the doctor disagree about several aspects of their discussion, including whether a formal admitting request was made.

Warren was sent home. Her son found her dead there three days later. An autopsy found that she died from sepsis caused by an untreated staph infection.

In 2015, Warren’s son sued Essentia, which later settled confidentially. A second lawsuit was filed against Fairview and Dinter.

“Fairview and Essentia had a working agreement that it would be Fairview that took these calls and did the admissions,” said Robert King of the Ciresi Conlin law firm, who represents the family. “In doing so they exposed themselves under the facts of this case.”

A Fairview spokesman said the company will continue to defend the lawsuit.

“Dr. Dinter’s response was appropriate based on the limited information provided,” the company said in a written statement. “As the majority opinion made clear, the merits of the claim remain to be determined, and we believe Fairview and Dr. Dinter will be found to have acted appropriately.”

Now that the physician-patient relationship standard has been removed, the case is likely to hinge on a legal concept known as “foreseeability of harm.”

“Is it predictable that the patient about whom you are being asked could be injured if your advice is wrong or if it is negligent?” said Pope. “That question needs to be answered by the trial court.”

The case law on foreseeability is not extensive, Pope said, which will create uncertainty.

“The health care profession is very risk averse,” he said. “So, in the face of uncertainty, they will limit risk even when that is not actually warranted.”

Indeed, the MMA and the Minnesota Hospital Association both raised concerns that the opinion will have a chilling effect on medical decisionmaking.

“Thousands of times every day, physicians and clinicians call on others to give their informal opinions,” said Dr. Rahul Koranne, chief medical officer of the hospital group. “This decision will not serve Minnesotans and has the potential to increase health care costs.”

But while the court was clear that the physician-patient relationship was not a malpractice requirement, it also sought to set some boundaries.

“Our decision today should not be misinterpreted as being about informal advice from one medical professional to another,” the opinion said. “This case is about a formal medical decision.”