'Some nations have a gift for ceremonial," wrote the future third Marquess of Salisbury, Lord Robert Cecil, after watching Queen Victoria open parliament. "No poverty of means or absence of splendour inhibits them from making any pageant in which they take part both real and impressive. Everybody falls naturally into his proper place, throws himself without effort into the spirit of the little drama he is enacting and instinctively represses all appearance of constraint or distracted attention."

What was arguably true for 19th century Britain (Cecil, as it happens, believed that Britain did not possess that gift) is no less so for 21st century America. As one party convention ends and another begins (hurricane permitting), we are halfway through a fortnight of ticker tape, talking points, balloons and bluster.

There was a time when these conventions meant something more than mere pageantry. They were the place where arguments were made, platforms thrashed out and delegates wooed with policy. But like British party conferences, conventions are now essentially media events at which the media enjoys neither particular access, information nor, for the most part, insight. The result is two weeks of propaganda rolled out like a well-choreographed marketing campaign and faithfully transmitted by supine outlets.

Like most acts of ceremony, form has long surpassed content. The further they have strayed from the substance the more the symbols matter. Strip away the high-minded commentary and you are left with two patriotic parades steeped in electoral rivalry and masquerading as a celebration of democratic culture.

As far as pageantry goes, they could certainly be worse. At least in these there are no gilded coaches, crowns, ermine or wigs. And yet despite the slew of historic candidacies - first Barack Obama and now Sarah Palin - it seems as though this year America's political class has less to celebrate than ever.

For the conventions do not just mark the beginning of a new presidential cycle but the passing of an old one. The fact that this administration has been criminally incompetent is now the stuff of water-cooler orthodoxy. The fact that it has been plain criminal is not. But it should be. Under George Bush the US has tortured, disenfranchised, lied, spied and, on more than one occasion, flouted its own constitution. Those who would not go along were fired or demoted. Those rulings it could not garner support for it simply classified or hid. Those inquiries it could not prevent it thwarted. When Major General Antonio Taguba tried to pursue his investigation of Abu Ghraib up the chain of command he was stopped. "I was legally prevented from further investigation into higher authority," he told the New Yorker.

Its violation of international law is ultimately a matter for the international community. But its violation of American laws is a matter for the American public. However, it is now clear that the political consequences of these transgressions will range from negligible to non-existent. The Bush administration should be led away in handcuffs - either indicted or impeached. Instead it is about to leave the scene of the crime in broad daylight while those tasked to police this democracy - notably politicians and the press - blind themselves with confetti.

Those who regard impeachment as merely a vindictive attempt to adjudicate the past display a chronic lack of imagination. True, it is not going to happen. But that makes it no less morally compelling or politically relevant to argue that it should. Trying to look ahead without acknowledging how you got to where you are is a surefire way to end up wandering around in circles. And the last place the Democrats want to be is where they were.

Take voter registration. Around this time last year the attorney general, Alberto Gonzales, was forced to resign amid allegations of perjury before Congress over his role in the politically motivated firing of seven attorneys. They were replaced by what his then chief of staff referred to as "loyal Bushies" on the advice of the White House. Five of the fired attorneys were in battleground states. They had irritated local Republicans by refusing to bring voter fraud cases targeted at loyal Democratic groups because of lack of evidence.

The congressional hearings were a farce. Gonzales said he "could not recall" more than 71 times in one day. Clearly he hoped we would forget too.

But in a year when voter rolls are swelling with the expectation of an unprecedented turnout it is crucial that we remember. A few weeks ago John McCain's campaign attorneys attended a national training session for Republican lawyers on election law, which included a session on identifying and responding to instances of voter fraud. Despite the justice department's own studies showing that voter fraud is extremely rare, Republicans are gearing up for mass intimidation in minority areas on election day. If the election is close expect to see Florida 2000 replayed from Virginia to Nevada. And if the challenges go to court, Gonzales's "loyal Bushies" will be there to hear the cases.

Such are the lasting consequences of Bush's crooked tenure. Casting him as inept and unethical is not difficult. He is the most unpopular president for six decades. Some have been loathed more - but none by so many for so long. But understanding how he managed to do it demands a wider lens.

For he could not do it alone. The US is not an elected dictatorship. The president is supposed to stand at the helm of a system of checks and balances. The reason there was no balance was because there were no checks. The real problem with the Bush years is not so much that he did what he did, but that he managed to gain the consent of America's political class in enabling him to do it. His political estrangement is not because he tried, only because he failed.

This has more or less been conceded by none other than the leader of the House of Representatives, Nancy Pelosi, who voted against the war in Iraq. When asked recently by the Nation why she took impeachment off the table before the 2006 elections, Pelosi answered: "What about these other people who voted for that war with no evidence ... Are they going to be voting with us to impeach the president? Where are these Democrats going to be? Are they going to be voting for us to impeach a president who took us to war on information that they had also?" In other words, for the Democrats to impeach the president they would first have to implicate themselves.

This is not to say the Democrats were equally culpable. But they were differently responsible, and cowed by accusations of lack of patriotism most of them abdicated that responsibility.

Asked to explain the administration's use of torture, the director of the 9/11 commission, Philip Zelikow, said: "Fear and anxiety exploited by zealots and fools." But there is, it seems, no price to pay for being a zealot or a fool in power. America will no doubt be anxious and fearful again some day. And for all the ceremonial hyperbole of this convention season, there is little to suggest that when that day comes the fools and zealots won't once again come out on top.

g.younge@theguardian.com