Donald Trump once infamously remarked while running for president, "I could stand in the middle of 5th Avenue and shoot somebody and I wouldn't lose voters." Though he's certainly not clever enough or historically astute to have known it, Trump was on to something. Just look at Chappaquiddick.

Though the word was once a ubiquitous reference in American politics, it barely registers anymore. That may change — for at least a brief interlude — thanks to the release later this week of Chappaquiddick , a narrative feature film depicting the July 1969 incident where then-Sen. Edward Kennedy (D-Mass.) drove his car off a bridge in Martha's Vineyard after a night of drinking, leaving Mary Jo Kopechne — a former aide to his late brother, Bobby — to die as he spent over nine hours concocting an alibi.

As the film depicts in horrifying detail — and as subsequent investigations far more thorough and competent than the one performed in the immediate aftermath by the Edgartown Police Department made clear — Kopechne died of suffocation, not drowning. The prevailing theory is that Kopechne was conscious and straining upward in the overturned car, gasping for hours in a pocket of air while trapped in the otherwise water-filled Oldsmobile. Had Kennedy exhibited slightly more concern for human life than his own political future, and notified first responders within the first few hours after the accident, the 28-year-old Kopechne likely would have been saved.

In Chappaquidick , Kennedy (played by Jason Clarke) is portrayed as self-pitying and manipulative, and at the same time infuriatingly entitled and easily manipulated. He vacillates between indulging a craven instinct to save his own skin and yearning for an opportunity to make penance and earn redemption.

Ultimately, the film's true theme reveals itself not as the Passion of Ted Kennedy, but the irresistible draw of tribalism.

A key plot point centers on the last surviving second-generation Kennedy belatedly steeling himself to do the right thing and make a confession with some semblance of truth to it, only to be thwarted by his domineering father, Joseph, Sr. — still plotting for another Kennedy in the White House — who plops his youngest son in a room with a who's who of the 1960s Democratic Party's heaviest hitters — fixers, lawyers, even former Secretary of Defense Robert McNamara.

Much of the film's second act is built around this brain trust's efforts to "frame the conversation," and in a rare moment where Kennedy exhibits a modicum of self-awareness at Kopechne's funeral, one of her closest friends rallies behind Kennedy, imploring him to not abandon his political future. Only a close Kennedy cousin serves as the film's conscience — consistently standing up against Teddy's deception and cowardice — and his reward is to be increasingly marginalized out of the tribe.

The film climaxes with the senator making a televised "confession." Though his prepared speech was self-serving to the point of absurdity, pockmarked with lies and omissions, and even included a reference to a mythical "Kennedy curse" — a montage of real news footage from 1969 of on-the-street interviews with Massachusetts voters provides the verdict to Kennedy's trial of public opinion. Most of the interviewees are overwhelmingly sympathetic, and even the ones who think Kennedy was wrong — as in, guilty-of-manslaughter wrong — still say they'd vote for him.

That's the unspoken lesson of Chappaquiddick . In a country with only two substantial political tribes, there is almost no transgression committed by a "leader" that can't be morally compartmentalized, and while most private citizens would be in prison for what Kennedy did, tribalism was his route to a legacy as "the lion of the Senate," where he was elected to serve nine terms before his death in 2009.

Nearly a half-century after the deadly incident, Kennedy tribalists chafe at the mere mention of Chappaquiddick as an affront to the Ted Kennedy legacy that they believe should be held as sacrosanct. MSBNC's Chris Matthews has been known to get his dander up when a Republican makes a Chappaquiddick reference during a TV appearance, and in the pages of The Daily Beast, Matthews once tried to spin Kopechne's death as the inspiration for Kennedy's advocacy for health care reform. Even Chappaquiddick director John Curran has inexplicably said he wouldn't have made this movie were Kennedy still alive.

Tribalism is why it took over two decades for Democrats to come around to the fact that the Bill Clinton's sexual transgressions were more than just grist for puritanical Republican outrage, but that his abuse of presidential power to silence and shame Monica Lewinsky should have cost him the presidency.

Republicans, for their part, would be delusional to think they are above such blind tribalism. After impeaching Clinton, the party of small government and family values nominated and elected Donald Trump — the serially adulterous, pussy-grabbing, crony capitalist with career-long mob ties. As an encore, Alabama Republicans nominated Judge Roy Moore, and though he ultimately lost his special election for Senate, he did so with the backing of the Republican National Committee and the President of the United States after multiple credible allegations of sexual assault, harassment, and sexual relationships with minors were made public.

One could argue that in the age of #metoo, social media, and cell phones with high definition cameras, the Chappaquiddick cover-up would have been nearly impossible to pull off today.

What remains totally possible, and indeed probable, is the political survival of a powerful man implicated in unforgivable acts. People need to believe in "leaders" to provide the tribe with purpose, and thanks to the timeless bipartisan scourge of the soul that is blind tribalism, the myth of the leader becomes more important than basic human morality.