Matt Lauer’s widely panned moderation of the NBC News Commander-In-Chief Forum, where he failed to fact-check Republican presidential nominee Donald Trump’s recurrent lie about opposing the Iraq War, shows precisely why it is paramount that moderators for the upcoming presidential debates correct misinformation and hold the candidates to an equal standard of truth-telling.

Lauer, who moderated the Commander-In Chief Forum hosted by NBC News and the Iraq and Afghanistan Veterans of America (IAVA) on September 7, let Trump lie twice that he “was totally against the war in Iraq.” Trump’s claim has been proved false time and time again, and because of the audacity of the lie, the media roundly castigated Lauer's slip.

With the first presidential debate looming, Lauer’s performance is a cautionary tale to the debate moderators, who will give voters one of the last chances to judge the candidates on the substance and breadth of their policy proposals.

Fox’s Chris Wallace, tapped as the moderator for the final debate, already outrageously conceded that he will not fact-check candidates’ lies, stating, “I do not believe it’s my job to be a truth squad.” With his concession, it’s imperative that the other moderators step up to the challenge of fact-checking candidates, because letting falsehoods go unchallenged is a disservice to voters and a strain on journalistic integrity.

Challenging mendacity in the presidential debates is paramount for a number of reasons, first and foremost being that Trump’s entire campaign has been grounded in lies and conspiracy theories. PolitiFact found that 71 percent of Trump’s claims are either “mostly false,” “false,” or “pants on fire.” As Huffington Post senior media reporter Michael Calderone explained, failure to fact-check lies in the debates “leaves the viewing public with a ‘he said, she said’ situation when the journalist picked to be onstage could say, decisively, who is right.” This, in turn, enables misinformation -- an injustice to voters -- and normalizes this behavior -- a threat to democratic and journalistic processes. New York Times reporter Yamiche Alcindor unequivocally said that, moving forward, journalists and reporters have a duty to fact-check lies and inconsistencies:

I think last night we saw Donald Trump say that he did not support the war in Iraq. Many people have fact-checked him and said that that's a false statement. BuzzFeed broke that big story saying here is him on Howard Stern saying that, that he does support the war. So I think being able to do that as journalists, we have to do that. Even if it's tenuous and we want to move on to the next question and we want to have multiple broad conversations, we have to stop and say, wait, you really need to answer this question.

Another worry for debate moderators’ passivity in the face of lies is the growing concern that Trump is being “graded on a curve,” where so long as he doesn’t “vomit all over himself and [he gives] a decent” performance, he’ll succeed. Failing to fact-check Trump’s lies during a debate will feed into the growing media tendency to lower the bar for Trump compared to Democratic presidential nominee Hillary Clinton.

As CNN’s John Berman said, “If the bar for Donald Trump is not embarrassing himself, what does that mean heading into the debates?”

Given that Trump’s accusations of media bias have already seemingly influenced the debate moderator selections, Lauer’s performance will hopefully encourage Lester Holt, Martha Raddatz, Anderson Cooper, and Chris Wallace to strengthen their fact-checking skills and harden their resolve to ensure the presidential debates are grounded in truth and reality.