The United Nations special rapporteur on the right to health has called on the US supreme court to uphold the right to abortion in America or risk undermining international human rights law and threatening that right elsewhere in the world.

The special rapporteur, Dr Tlaleng Mofokeng, is one of just a handful of global observers whose mandate is to travel the world defending human rights.

Mofokeng has argued in a brief filed in a US court that overturning abortion rights would violate international human rights treaties ratified by the US, including the convention against torture, should women be forced to carry pregnancies to term.

In an interview, Mofokeng told the Guardian she could have filed a brief on abortion rights, “in any other court, in any other abortion case,” globally. However, she chose the US courts because of the direct threat posed to abortion rights in the supreme court’s upcoming session.

“We have this joke among us that when the US sneezes the rest of the world catches a [cold],” said Mofokeng. “So we know that politically that what happens in the United States… does have an impact in precedents elsewhere in the world.”

Mofokeng’s brief was filed ahead of oral arguments in Dobbs v Jackson Women’s Health Organization, a case advocates fear will undermine abortion rights nationally. Dobbs poses a direct threat to Roe v Wade, the landmark 1973 case that established a Constitutional right to abortion based in privacy.

Roe invalidated dozens of state abortion bans and restrictions, and allowed people to terminate a pregnancy up to the point a fetus can survive outside the womb, generally understood to be about 24 weeks gestation. A full term pregnancy is 39 weeks.

“If that gets overturned, it has catastrophic implications, not just for the US,” said Mofokeng, who said she feared overturning Roe would embolden global attacks on reproductive rights.

Mofokeng is also a practicing doctor and well-known sex-positive author in South Africa. Most often, she goes by “Dr T”, an informal title which underscores the empathy in her academic analysis. Her most recent UN report outlined the challenges Covid-19 posed to reproductive rights, and how colonialism continues to affect global policies on reproduction, from sterilization to abortion bans.

“It means that even those people who are conservative, who are anti-rights, in any country in the world, will actually now start referencing the US court as an example of jurisprudence that should be followed,” said Mofokeng. “And this is why this is so dangerous”.

In Dobbs, the court will consider whether Mississippi can ban abortion at 15 weeks gestation. For the court to uphold Mississippi’s law, it would require the court to rewrite standards that determine whether abortion restrictions are constitutional. Advocates fear that could once again allow states to severely restrict or ban abortion.

A majority of the court’s nine justices would need to agree to rewrite such standards. Conservative justices hold a 6-3 supermajority on the court. Many observers view the court’s decision to take the Mississippi case as an ominous sign. About six in 10 Americans believe abortion should be legal in “all or most cases”.

“If Roe … [were] overturned, many US states will implement bans or near-bans on abortion access that will make individual state laws irreconcilable with international human rights law,” the brief argued. “This would cause irreparable harm to women and girls in violation of the United States’ obligations under the human rights treaties it has signed and ratified.”

While the US has not ratified several United Nations treaties, it has ratified the convention against torture, which Mofokeng’s brief argued would be violated if states were allowed to ban abortion.

“The denial of safe abortions and subjecting women and girls to humiliating and judgmental attitudes in such contexts of extreme vulnerability and where timely health care is essential amount to torture or ill treatment,” Mofokeng’s brief said, citing a 2016 report by the rapporteur on torture and other cruel, inhuman or degrading treatment or punishment.

Conversely, Mofokeng’s brief argued, contrary to Mississippi’s assertions, that “the right to life emanating from human rights treaties does not apply prenatally,” and that the “overwhelming trend for the past half-century has been toward the liberalization of abortion laws worldwide”.

Further, since the court has accepted the Dobbs case, it also allowed a six-week abortion ban to go into effect in Texas in September, effectively allowing the nation’s second largest state to nullify Roe within its borders. Experts estimate that if Roe were overturned, roughly two dozen US states mostly in the south and midwest would immediately ban abortion.

Such bans would have immediate and direct consequences for women and people seeking abortions.

In one recent analysis, the Guttmacher Institute found 26 states are certain or likely to outlaw abortion should Roe be overturned. In just one example, that would require a woman seeking a legal abortion in Louisiana to travel to Kansas to access care.

“The rise in global anti-gender and anti-women’s rights is such that people will grasp at anything that seems to make their case solid,” said Mofokeng. And, she said, the case before the supreme court now relies on “non-medical, non-scientific” misinformation.

“It means we have a risk of now having global jurisprudence – or at least influences in the global world – using jurisprudence that’s ill-informed. And that’s very dangerous,” said Mofokeng. “To undo the court’s decisions takes decades, sometimes a lifetime – and that’s why it’s dangerous.”