So, at last the deal is done. For many -- and not just supporters of Jacob Zuma -- it will be a relief that the National Prosecuting Authority has decided to drop the charges against the man who will soon be president. A great exhalation for a country that has been holding its breath too long. We are sighing too, but for very different reasons.

This is a shameful day.

A deal stitched up in secrecy, amid a welter of as-yet-untested allegations, is the antithesis of our most basic principles. We agreed 15 years ago what kind of country we wanted to live in. There may have been room for interpretation of the details but on one thing we can be quite clear: this is not it.

Indeed, we know only the outlines of the representations made by Zuma's legal team to acting NPA boss Mokotedi Mpshe thanks to leaks and spin. It seems the NPA has been given credible evidence that Leonard McCarthy, the former Scorpions boss who was in charge of the investigation, was driven by his loyalty to former president Thabo Mbeki. It seems clear too that he lied to colleagues and abused his office.

If those allegations are borne out they will show just how deeply the institutions of the state have been compromised by the internecine warfare of the ANC.

Our response must not be -- cannot be -- to wish away this over­whelming and perhaps destabilising reality. Many will suggest that we should; that South Africa cannot withstand an accounting of what has been done by our leaders in the arms deal, in the battle to succeed Mbeki and in the prosecution of Zuma.

They are wrong.

Nothing could be more destabilising than a solution that leaves us without answers, living with both Mbeki's tainted legacy and Zuma's compromised rule. Nothing could be more destabilising than the thorough collapse of the rule of law that this decision represents.

That does not mean Zuma should be found guilty. It means that the evidence against him and against the NPA must be tested in court, the most painful details put in front of the entire country, not just Willie Hofmeyr and Mpshe. We simply cannot afford anything less.

There must be consequences, too, for the security agencies that have turned their energies so readily to fighting party battles. An investigation into alleged abuses by the NPA, and McCarthy in particular, must be undertaken, and conducted thoroughly. It must be matched by an equally thorough investigation into how evidence collected by the National Intelligence Agency and crime intelligence found its way into Zuma's hands.

Charges, if warranted, should follow. And if Mbeki is implicated either in arms deal corruption or manipulation of the Zuma prosecution he must be investigated too.

We can handle it. After all, we defeated apartheid.

In the short term civil society, political parties and concerned individuals must act to prevent this travesty. The decision to drop charges must be scrutinised rigorously and openly, using all the legislative and constitutional instruments at our disposal. That can only happen by way of a judicial review -- ladies and gentlemen, draft your papers.