In a speech last week, Hillary Clinton took her befuddlement with Donald Trump and dropped it squarely at the feet of America’s mental health professionals. “I’ll leave it to the psychiatrists to explain his affection for tyrants,” she said, in response to comments Trump had made marveling at the political effectiveness of North Korean dictator Kim Jong Un.

She’s not the first person to suggest the Republican presidential candidate could use a session on the couch. Back in November, Vanity Fair got five psychiatrists and psychologists to weigh in on Trump’s mental health. But while Clinton is free to imply anything she wants about her opponent’s sanity, the experts in sanity (or lack thereof) are supposed to keep mum. Both psychiatrists and psychologists operate under ethical rules that prevent them from offering professional diagnostic opinions about the mental health of public figures they have not personally examined. The American Psychiatric Association’s version of this is known as the Goldwater Rule — named for another polarizing Republican presidential candidate.

The rule has its roots in the September/October 1964 issue of a magazine called Fact, which was entirely devoted to parsing the results of a survey the editors had sent to more than 12,000 psychiatrists. The survey only had one question: “Do you believe Barry Goldwater is psychologically fit to serve as president of the United States?”

Most of the psychiatrists — 9,939 of them, to be exact — didn’t respond. Of those who did, 571 said they didn’t know enough about Goldwater to answer, and another 657 declared him fit as a fiddle. But 1,189 psychiatrists said “no,” and many of them added colorful commentary that the magazine reprinted under a headline (“FACT: 1,189 Psychiatrists Say Goldwater is Psychologically Unfit to Be President!”) that conveniently left out the fact that they didn’t represent a majority opinion. The Republican presidential candidate was called “paranoid” and “a dangerous lunatic.” One respondent suggested that Goldwater had “a stronger identification to his mother than to his father” — fighting words in 1964 America, apparently.

In the aftermath, Goldwater sued Fact (and won), Fact went defunct, and the American Psychiatric Association tried to make sure that none of this would ever happen again. The result was Section 7.3 of the APA’s Principles of Medical Ethics:

On occasion psychiatrists are asked for an opinion about an individual who is in the light of public attention or who has disclosed information about himself/herself through public media. In such circumstances, a psychiatrist may share with the public his or her expertise about psychiatric issues in general. However, it is unethical for a psychiatrist to offer a professional opinion unless he or she has conducted an examination and has been granted proper authorization for such a statement.

Or, as Ezra Griffith, professor emeritus of psychiatry at Yale and a member of the APA’s Ethics Committee, put it: “If you’re going to talk to the press and spread stuff on your opinions, it’s important to at least say very clearly, ‘I have not examined this individual and therefore much of what I’m saying is sort of mystical black magic.’ ”

The Goldwater Rule is the reason psychiatrists who comment in celebrity gossip magazines always first clarify that they have not treated Joaquin Phoenix, Lisa Marie Presley, Britney Spears, etc. It’s also why The Atlantic’s June cover story — a long personality analysis of Donald Trump written by Northwestern University psychologist Dan McAdams — was very careful to stay far away from the realm of medical diagnosis.

The idea of psychoanalyzing public figures — especially public figures you don’t like — can be appealing, McAdams told me. We feel like we have lots of information about them and who they are. In fact, he has received angry letters from readers upset that he didn’t diagnose Trump with a personality disorder. But mental health is still health, he said, and labeling Trump from afar would be no different than diagnosing President Obama with leukemia, sight unseen.

What’s more, McAdams said, the basis of diagnosing a mental health disorder is that the person feels disordered. Human behavior and personality exist on a spectrum and the thing that makes the difference between, say, somebody who is a bit scatterbrained and somebody with ADHD is that the latter is debilitated by the symptoms they experience and has trouble functioning in society. And it’s hard to make a case for that being true of somebody successfully running for president of the United States. “Whether you like him or not, he seems to function,” McAdam said.

As evidenced by the Vanity Fair, story, however, not all mental health professionals believe it’s that clear cut. What’s more, disagreement over the Goldwater Rule isn’t as simple as “here’s what psychiatrists believe and here are a few bad apples who break the rules.” Last week, the Journal of the American Academy of Psychiatry and the Law (JAAPL) published a paper questioning the foundations of the Goldwater Rule and arguing that the rule stifles psychiatrists’ ability to speak their conscience. And that perspective is nothing new. The Goldwater Rule has been controversial within the field of psychiatry since it was enacted in 1973, said Brian Cooke, a forensic and clinical psychiatrist at the University of Florida who wrote a 2014 paper, also published in JAAPL, arguing in favor of the rule.

The controversy centers around two things. First, said Jerome Kroll, professor emeritus of psychiatry at the University of Minnesota and an author of the 2016 paper, it’s disingenuous to ask psychiatrists to tiptoe around the diagnosing of public figures while still commenting on diagnoses — talking about narcissism, but not about whether Donald Trump is a narcissist, for instance. Especially when psychiatrists are allowed to diagnose dead people — a specialty called psychohistory — using data that’s not much different from what someone might use to diagnose the living Trump.

Second, Kroll and his co-author, independent clinical psychiatrist Claire Pouncey, object to the way the rule stifles a psychiatrist’s ability to speak his or her mind. Certainly, Pouncey told me, psychiatrists shouldn’t run around shooting their mouths off about things they haven’t deeply studied. But it’s impossible, she said, to distinguish between the psychiatrist as a professional and the psychiatrist as a person — and that person might feel a very real ethical obligation to talk about their perspective on the mental health of a public figure angling for a position of power over the whole country. “We don’t dispute the spirit of the law,” she said. “But it’s not a real distinction and it shouldn’t be upheld by a professional body.”

All the more so because, as far as anyone I interviewed can tell, it’s never been enforced. What’s the point of having a law on the books that has no teeth?

So, does that mean Pouncey would take a stab at diagnosing Donald Trump? She declined the opportunity, saying instead that Trump behaves so extremely that he makes her uncomfortable as a person.