Lee Hamilton and Tom Kean – the co-chairmen of the 9/11 Commission – are the prototypical Wise Old Men of Washington. These are the types chosen to head blue-ribbon panels whenever the US government needs a respectable, trans-partisan, serious face to show the public in the wake of a mammoth political failure. Wise Old Men of Washington are entrusted with this mission because, by definition, they are loyal, devoted members of the political establishment and will criticise political institutions and leaders only in the most respectful and restrained manner.

That is why it was so remarkable when Hamilton and Kean, on 2 January 2008, wrote an op-ed in the New York Times repeatedly accusing the CIA and the Bush White House of knowingly "obstructing" their commission's investigation into the 9/11 attack. As many imprisoned felons can attest, the word "obstruction" packs a powerful punch as a legal term of art signifying the crime of "obstruction of justice", and yet, here were these two mild-mannered, establishment-protecting civil servants accusing CIA and Bush officials of that crime in the most public and unambiguous manner possible.

What triggered this duo's uncharacteristic accusatory outburst was the revelation that the CIA had purposely destroyed numerous videos of interrogation sessions it had conducted with al-Qaida operatives (destroyed were 92 videos, showing hundreds of hours of interrogations). The 9/11 Commission had repeatedly demanded, with the force of law behind it, that all such interrogation materials be provided to it. Numerous courts presiding over lawsuits relating to torture allegations against the CIA had also ordered that any such videos be produced.

But with those orders pending, the CIA destroyed the very evidence it was legally compelled to preserve. With at least the knowledge, if not direction, of White House officials, they did so almost certainly with the intent of preventing the world from seeing how they treated detainees in their custody – with torture – but the effect was to prevent the 9/11 Commission and multiple courts from learning what al-Qaida operatives said (or did not say) about 9/11 and other matters under investigation.

That is why the CIA's actions were so clearly criminal: destroying evidence one knows is relevant to a lawful investigation or a judicial proceeding is the very essence of "obstruction of justice". Individuals are routinely prosecuted and imprisoned in the US for such acts in far less serious cases. So egregious and deliberate was the CIA's criminality – purposely destroying evidence relevant to the most significant terrorist attack in history on US soil – that not even Hamilton and Kean were willing to paper over it.

Despite all that, there have been no legal consequences whatsoever for the crimes of these CIA officials. Last November, the Obama justice department – following the administration's all-too-familiar pattern of shielding Bush-era crimes from acountability – announced it was closing its criminal investigation into the matter with no charges filed. And this week, a federal judge, whose own order to produce these videos had been violated by the CIA, decided that he would not even impose civil sanctions or issue a finding of contempt because, as he put it, new rules issued by the CIA "should lead to greater accountability within the agency and prevent another episode like the videotapes' destruction".

In other words, the CIA has promised not to do this again, so they shouldn't be punished for the crimes they committed. Aside from how difficult it is, given the agency's history, to make that claim without triggering a global laughing fit, it is also grounded in a principle of leniency rarely applied to ordinary citizens. After all, most criminal defendants caught up in the life-destroying hell of a federal prosecution are quite unlikely to repeat their crimes in the future, yet that fact is no bar to punishing them for the illegal acts they already committed.

What actually produced this astounding outcome is the two-tiered system of justice that is now fully entrenched in the US: one in which ordinary Americans are subjected to a brutally harsh and unforgiving system of punishment, while political and financial elites are vested with virtually full-scale immunity for even the most egregious of crimes. It is that warped "justice" system that has caused Americans to witness the construction of the world's largest penal state for ordinary citizens at the very same time that the most destructive elite crimes – a worldwide torture regime, Wall Street plundering on a massive scale, illegal domestic eavesdropping, an aggressive war in Iraq that killed at least tens of thousands of innocents – have gone completely unpunished.

As I spent the last 18 months writing my forthcoming book on this two-tiered justice system, I genuinely expected, as I recount there, that there would be indictments in the CIA video case, thus providing a counter-example to the book's argument that elites are now immune from the rule of law. "Even our political class," I wrote, "couldn't allow lawbreaking this brazen to go entirely unpunished." Alas, as Wednesday's court ruling (pdf) demonstrated, I was wrong: there is no elite criminality too egregious to enjoy this shield of immunity. Thus can the CIA purposely destroy evidence it has been ordered to produce both by a congressionally-created investigative commission and multiple courts – and do so with total impunity.