For many years now, some critics of former President Donald Trump have called into question his mental health status and cognitive capabilities, albeit without the benefit of a personal examination to support their conclusions.

That includes his estranged niece, Mary Trump, a clinical psychiatrist who has politically opposed her uncle for years, who recently warned during a cable news appearance that the former president is suffering the effects of "untreated psychiatric disorders," Newsweek reported.

In making that public diagnosis for a public figure she has not personally examined, however, Mary Trump appears to have violated a key ethical guideline of her psychiatric profession.

Trump diagnosed from afar by niece with "untreated psychiatric disorders"

On Thursday, Mary Trump appeared on MSNBC's "The Last Word" with host Lawrence O'Donnell and spent the entirety of the segment trashing her uncle, former President Trump, who is the likely Republican nominee set to face off against President Joe Biden in November in a rematch of the 2020 election.

O'Donnell shared his view of how the former president has become increasingly incoherent over the past decade or so, to which Mary Trump replied that it was "obvious" to her that "This is a person who has untreated psychiatric disorders. And any untreated disorder of any kind worsens over time, as long as it remains untreated."

"So, it makes perfect sense that somebody who is as unhealthy as he is, who is under the extraordinary amount of stress he is under, would have a harder time holding it together cognitively," she continued.

Niece asserts uncle is no longer able to coherently stick to a point

Mary Trump wasn't finished yet, though, and concerning O'Donnell's assessment of the former president's increasing incoherence in his public remarks, she stated, "Donald was always quite good when he was younger at sticking to a point. And he knew certain things about his business, so he could say perfectly reasonable statements with confidence."

"And let’s be fair, he was very good at being in the media," Trump continued. "And that is one of the main reasons my grandfather chose him to be his successor because he had that kind of presence."

"What is so fascinating about this chapter in his life is that he has finally reached the end of the road," the niece later added of her uncle. "When he was taking over for my grandfather, or when he was my grandfather’s successor, and the one who is going to fill my grandfather’s ambitions, he did not need skill -- skill as a real estate developer -- he just needed the skill as the arrogant, self-confident, brash guy who played well on television. My grandfather always had hundreds of millions of dollars to prop him up."

Did Mary Trump just violate a key APA ethics rule?

To be sure, Mary Trump is well within her rights to politically oppose and speak out against the former president, but she may have crossed the line and violated a key ethical principle of the American Psychiatric Association, known as "The Goldwater Rule," by including an apparent diagnosis of his mental health without the benefit of a personal examination.

"We at the APA call for an end to psychiatrists providing professional opinions in the media about public figures whom they have not examined, whether it be on cable news appearances, books, or in social media," the organization said in a 2018 statement. "Armchair psychiatry or the use of psychiatry as a political tool is the misuse of psychiatry and is unacceptable and unethical."

"The ethical principle, in place since 1973, guides physician members of the APA to refrain from publicly issuing professional medical opinions about individuals that they have not personally evaluated in a professional setting or context. Doing otherwise undermines the credibility and integrity of the profession and the physician-patient relationship," the statement added. "Although APA's ethical guidelines can only be enforced against APA members, we urge all psychiatrists, regardless of membership, to abide by this guidance in respect of our patients and our profession."

As for the concerns of Mary Trump and others about the former president's mental health, a recent NBC News poll showed that around 48% of registered voters had "major" or "moderate" concerns about Trump "not having the necessary mental and physical health to be president for a second term," while a combined 76% had similar "major" or "moderate" concerns about President Biden in that regard.