You’ve been warned: The fate of the planet hangs in the balance if Kerry Kennedy is convicted of drugged driving in a New York trial that gets under way Monday.

Robert F. “Bobby’’ Kennedy Jr., 60, called me the other day to plead for compassion for his misunderstood sister, a lawyer and professional human-rights activist born Mary Kerry Kennedy.

“Kerry’s been instrumental in freeing political prisoners and dissidents from around the globe from imprisonment and torture,” Bobby told me.

He argued that political agitators all over the world could be locked up and tortured if his sister, 54, is convicted in Westchester County for being hell on wheels. Africans might be tormented or killed for being gay.

If convicted of driving while ability impaired by drugs — a misdemeanor — she fears she’ll be barred from entering countries like Canada, New Zealand and Australia, and thus be unable to perform her important work.

Like her brother, Kerry is the child of slain Sen. Robert F. Kennedy. Their uncle was President John F. Kennedy. Kerry is also the ex-wife of Gov. Cuomo.

Last month, Kerry was on her way to meet her brother, a lawyer and environmental activist; their documentary filmmaker sister Rory, 45; and Bobby’s actress gal pal, Cheryl Hines, 48, at the Sundance Film Festival in Utah when she made an abrupt, globe-trotting ­U-turn.

Kerry received an urgent call from South African social-rights activist Desmond Tutu, who asked her to fly to Africa immediately. At Kerry’s request, the retired Anglican bishop and Nobel Peace Prize winner had set up a meeting between Kerry and the president of the African nation of Uganda, who supposedly was about to sign into law the so-called “Kill the Gays” bill.

So Kerry instead boarded a plane at JFK Airport and high-tailed it to Uganda’s capital city of Kampala, where, the story goes, she succeeded in saving the gays.

“You’ve changed my mind. We can’t go on executing people because they were born that way,” Ugandan President Yoweri Museveni told Kerry, according to a friend of hers.

Well, that’s one version of the story.

“She has freed hundreds of political prisoners from Uganda to Nigeria to Kenya and Mexico because she has access because of her name,” Bobby enthused, adding, “That doesn’t mean she’s above the law.”

Is Bobby loyal? Or delusional?

I haven’t a clue what this world-saving business has to do with the case of a privileged woman and a highway smashup. I do know that Kerry could have hurt or killed someone, even herself, when she got behind the wheel of her silver 2008 Lexus SUV on the morning of July 13, 2012, allegedly while under the influence of the sleeping pill Ambien. She did, in fact, crash the vehicle into a tractor-trailer truck on Interstate 684 near her home in the tony town of Bedford and then continued driving.

A motorist finally found her slumped over her vehicle’s steering wheel, unable to walk or see straight.

Luckily, no one was injured.

Kerry initially told a police officer that she might have mistakenly taken Ambien instead of her thyroid medication. Then, four days later, she stood outside the tiny Town of North Castle Justice Court in Armonk — the case has since moved to roomier quarters in White Plains — and announced that her doctors believed she suffered a “complex partial seizure” at the time of the wreck, caused by an earlier head injury.

Wrong.

Toxicology test results revealed that Kerry had ingested zolpidem tartrate, the generic term for Ambien. Her lawyers now contend that she innocently mixed up her pills.

Kerry is president of the Robert F. Kennedy Center for Justice and Human Rights. But how effective is she at righting planetary wrongs?

It turns out that Uganda’s gays never faced certain death.

By the time an anti-gay bill had passed through the country’s legislative body in December, lawmakers had removed execution as punishment for certain homosexual acts and replaced it with penalties up to life in prison, still pretty harsh.

When Kerry and members of her crew met with President Museveni on Jan. 18, he told the activists he would not sign a “fascist” anti-gay bill into law.

Then he changed his mind.

Museveni said through a spokesman on Feb. 14 that he intended to sign the bill “to protect Ugandans from social deviants.”

President Obama condemned the measure.

If convicted, Kerry could be sentenced to up to a year in jail, but a legal source said she’d likely be ordered by a judge to perform community service.

Kerry plans to testify in her own defense at trial, giving observers a glimpse into the mind of a globe-trotting do-gooder.

One who can’t own up to doing anything wrong.