Among former presidents, there’s an unwritten rule: Once you leave the game, you don’t stand on the sidelines and criticize the man who took your place. You never heard George H.W. Bush attack Bill Clinton. Never heard Clinton slamming George W. Bush. And, to his credit, you haven’t heard a peep from George W. Bush ever since he went back to Dallas.

There’s no law against it. It’s just considered beneath the dignity of the sacred office he once held for a former president, after leaving office, to turn himself into a political attack dog.

The same rule applies to former vice presidents. When’s the last time you heard from Dan Quayle? Or Al Gore? Realizing they have even less standing to be critical, most former vice presidents also refrain from cheap political attacks. With one notable and shameful exception: former Vice President Dick Cheney, who never stops lashing out. Cheney, in fact, says the same rules don’t apply to him. As he told Politico’s Michael Allen this week: “The president made the decision that he wasn’t going to criticize his successor. That’s his call, with the precedent that was set by his father. I’m not bound by those strictures.”

Thus unbound, over the last six years Cheney has unleashed a barrage of attacks against President Obama, which former President Bill Clinton dubbed “unseemly.” On CNN recently, he told Jake Tapper he’d never met a worse president: “I think he is the worst president of my lifetime. I fundamentally disagree with him. I think he’s doing a lot of things wrong.” Cheney then congratulated Speaker John Boehner for planning to sue Obama. I wonder what he would have called Nancy Pelosi if she’d ever sued George Bush?

Cheney’s most hate-filled tirade came in a June 17 op-ed he penned for the Wall Street Journal with his daughter and failed Senate candidate, Liz. Accusing Obama of “abandoning” Iraq by withdrawing American forces in 2011, he suggested Obama would only be remembered “as the man who betrayed our past and squandered our freedom.” As if that weren’t mean enough, Cheney then dropped his nuclear bomb: “Rarely has a U.S. president been so wrong about so much at the expense of so many.”

Oh, really? Does Cheney think our memories are so short? Unfortunately, for him, we remember that many of the problems Obama inherited, and is still struggling with, are a result of the failed policies of the Bush administration: a bloated deficit caused by two rounds of tax cuts for the top 2 percent; the worst economic meltdown since the Great Depression; a disaffected world after years of go-it-alone, cowboy foreign policy; America’s No. 1 enemy still on the loose; and two costly wars with no clear mission and no end in sight.

As for Iraq, we also remember that our biggest mistake was not pulling troops out too soon, but invading Iraq in the first place. And who was the architect of that decision? Who was the biggest cheerleader for the Iraq war in the Bush administration? Vice President Dick Cheney. He wasn’t alone, but it was primarily he who insisted that Iraq had weapons of mass destruction. He who claimed Iraq had nuclear weapons and mobile missile launchers with which to blast them toward Israel. He who warned us that Iraq was a direct threat to the United States. And when the CIA couldn’t find evidence to back up any of his claims, he ordered them to keep digging.

Add up the lies told about Iraq, add up the cost in American lives and dollars, and it’s clear that Cheney’s loaded phrase – “Rarely has a U.S. president been so wrong about so much at the expense of so many” – is a perfect encapsulation of the Bush administration, for which Dick Cheney bears a great deal of responsibility and for which, privately, Bush himself must suffer a few regrets.

Indeed, in his masterful book “Days of Fire,” Peter Baker, chief White House correspondent for the New York Times, tracks how the relationship between Bush and Cheney gradually disintegrated, the longer into his term and the more Bush realized how he’d been stampeded into bad decisions by his number two. In 2013, on C-SPAN, Bush acknowledged that they seldom speak, then hastened to add: “But he lives in Washington, and we live in Dallas.”

Yes, but. Geography’s not the issue. The problem’s not where Dick Cheney lives. The problem is, unlike his former boss, Cheney just won’t shut up.

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