If you're like me, your parents probably taught you that interrupting while others are speaking is rude. But sometimes it's necessary and there's a right way and a wrong way to do it. In the second Democratic Presidential Debate, Kamala Harris demonstrated exactly how to do it right.

Imagine you're one of 10 people in a debate, fighting for a bit of the spotlight to make your point, make your name, and try to convince viewers they should support you. What's the best way to achieve that goal? Should you scrupulously follow the rules of the event, waiting for your turn and demonstrating what a good team player you are? Should you jump in and grab whatever time you can, interrupting other candidates to do so, and ignoring the moderators when they call for you to stop? The right approach lies somewhere in the middle--but in presidential debates, interrupting often works to a candidate's advantage.

The first Democratic presidential debate took place over two consecutive evenings to accommodate a crowd of 20 candidates. As always, the journalists who moderated them laid out the rules at the beginning of each debate. Candidates would only have so much time to speak, they said. They would be ruthless if necessary, they warned. 

All of that was a lie, which was no surprise to anyone with a history of watching political debates. Candidates tend to jump in and interrupt each other, talk over each other or even shout each other down and moderators tend to let it happen in the name of more interesting television. New York mayor Bill de Blasio, a candidate with little chance of winning the nomination, was the first to grab unscheduled TV time by interrupting and jumping in on someone else's answer. He was allowed to proceed, which emboldened the others to do the same.

But not all of them. I was carefully watching the debate looking for lessons to draw from it and I  still missed the most obvious one: Men were doing nearly all the interrupting, and consequently getting most of the air time. Of the 10 candidates on stage, three were women, but they were responsible for much less than 30 percent of the interruptions, as columnist David Leonhardt noted in the New York Times the following morning.

That's something of a norm, he wrote. In another Times piece, women reported that not only are they routinely interrupted by men but that they also face a double standard. When women interrupt they're perceived as angry or bitchy rather than forceful and decisive, which is how men tend to be seen when they interrupt. And women are seen as whiny if they complain about being interrupted. One woman said she learned by experience that she could only speak up about an interruption with impunity after the same man had interrupted her four times.

Sure enough, men interrupting women seems so normal even to me that until I read Leonhardt's piece I hadn't thought at all about how often the men at the first debate interrupted and talked over the women there. But once I did, I realized how much difference it made as to whose voice was heard. By polling and national prominence, Elizabeth Warren was unquestionably the frontrunner in the first debate, but an analysis showed she spent less time speaking than Cory Booker or Beto O'Rourke, lesser candidates with a greater tendency to interrupt their opponents. It was yet another case where unspoken social norms amplified men's voices and stifled women's.

Night two.

But then came the second debate. By random chance, this group of candidates included four of the five frontrunners and all 10 had seen the first debate and learned the obvious lesson that they could interrupt each other with impunity. So they did.

But while they all did it, one candidate interrupted with a calm sense of authority that dwarfed everyone else on the stage and naturally commanded everyone's attention. That person was a woman, California senator Kamala Harris. When the debate devolved into everyone talking at once, she put an end to it with what was doubtless a prepared line about how the American people didn't want to see a food fight, they wanted to hear how they would put food on the table. When she jumped in after another candidate's comment about race and the moderators told her to stop, she shot back, "As the only black person on this stage, I would like to speak on the issue of race."

That brought cheers and the moderators relented and gave her 30 seconds to speak, which she used to call out former vice president Joe Biden for his opposition to integrating schools by busing. Harris noted that she herself had been bused to an integrated school. 

Because he'd been "invoked" as they put it, the moderators gave Biden 30 seconds to answer. He insisted that he wasn't against busing per se, but he believed those decisions should be made by states and cities, not the federal government. Harris jumped in again to disagree, saying that sometimes the federal government must intervene in local decisions because "there are moments in history when states fail to preserve the civil rights of all people." The audience cheered. Biden was left sputtering about his various civil rights accomplishments and then he abruptly dropped the argument, saying his time was up.

Most observers called Harris the clear winner of the second debate, and even the winner of both nights overall. It might not be enough to get her the nomination--before the event she was polling in fourth place, badly behind Biden, Vermont senator Bernie Sanders, and Warren. But she stood up to the men surrounding her, interrupting them when appropriate and coming off as forceful and authoritative rather than angry or whiny. That makes her a valuable role model for every woman who's ever been cut off, talked over, or shouted down by a man.