As my colleague Jon Schwarz notes, the head of the debate commission suggested on Sunday that fact-checking should be left to the candidates, not the moderators.

As it happens, we have a very good example of just how poorly that works, from the not-too-distant past of the first presidential debate in 2000, between Al Gore and George W. Bush.

All that lingered in the minds of many Americans after that debate, cemented by the “Saturday Night Live” parody, was Gore’s repeated use of the word “lockbox” to describe his plan to secure social security funding and the fact that, as the New York Times reported the next day, “At several points Mr. Gore sighed loudly at Mr. Bush’s answers.”

In retrospect, though, it is striking to realize that Gore’s frustration with Bush was largely driven by the fact that the Texas governor refused to admit that it was true that his planned tax cut would dole out nearly half of the money to “the wealthiest 1 percent” of Americans.

Gore repeated the charge 10 times throughout the debate, and each time Bush dodged, accusing his rival of using “fuzzy math.”

Looking back at the transcript, it is also remarkable that the debate moderator, Jim Lehrer — who hosted every first debate from 1988 to 2012 — refused to provide help to Gore in establishing that his analysis was entirely supported by the facts.

At one point, Lehrer even interrupted Gore’s real-time fact-check to turn the stage over to Bush. “I want to see if he buys that,” Lehrer said.

Later, when Gore returned to the fact that Bush was concealing the true cost of his proposal, saying “the surest way to threaten our prosperity, having a $1.9 trillion tax cut, almost half of which goes to the wealthy,” Lehrer testily observed, “I thought we cleared this up a while ago.”

Gore was of course correct, and the Bush tax cuts, tilted heavily in favor of the 1 percent, ended up massively increasing income inequality and eventually cost the United States government at least $2.8 trillion in tax revenue.

That lost money could have largely covered the neglected infrastructure spending on roads, bridges, and schools the federal government has not provided in the meantime.