Lester Holt challenged Republican presidential nominee Donald Trump on claims he made during the first presidential debate, highlighting the value of having moderators who are willing to fact-check false claims in real-time.

During the September 26 presidential debate, moderator Holt challenged Trump on inaccurate claims the candidate made about releasing his tax returns, promoting the birther conspiracy, and supporting the war in Iraq:

Holt stayed out of much of the debate, but intervened when Trump made glaring factual errors about his own record. Holt’s restraint made his fact-checks more powerful, drawing significant attention to Trump’s falsehoods, and tripping up the candidate before he could turn those lies into attacks on his opponent.

Holt’s fact-checking likely had a significant impact on the millions of voters for whom the debate was a first hard look at the candidates. But it’s just one battle in the larger struggle over whether moderators should fact-check the candidates in real-time. Both campaigns have argued over the issue, with Trump’s campaign predictably arguing that moderators should stay out of factual disputes during the debates.

That argument has gained some notable supporters -- NBC’s Matt Lauer was harshly criticized for failing to fact-check Trump’s claims about opposing the Iraq War during this month’s presidential forum. Fox News’ Chris Wallace, who will moderate the final presidential debate, has already said he doesn’t believe it’s job to be a “truth squad.” Even the executive director of the Commission on Presidential Debates told CNN recently that moderators shouldn’t be fact-checkers.

But leaving the fact-checking to the candidates, rather than the moderators, can contribute to spreading misinformation among voters. Research suggests that audiences that watch this kind of “he said/she said” debate end up feeling less capable of figuring out the truth, causing some to give up trying to resolve factual disputes altogether. Moderators who can carefully choose to intervene during important factual disputes offer a powerful antidote to that kind of passive misinformation.

Lester Holt’s performance set a powerful example of the value that measured fact-checks can have in keeping candidate’s honest. If the other debate moderators follow his lead, they’ll be doing voters, and the whole of campaign journalism, a real service.