Who knows whether John Banks will be found guilty next year, only the courts can decide. But in the court of public opinion, a trial is as bad as a conviction

It all comes back to two cheques and a mattress. And now John Banks is paying a high price for the donation he received from Kim Dotcom during the 2010 Auckland mayoral election, having announced that his political career will sputter out over the next year.

You know the story well enough. John Banks was standing for a second term as mayor of Auckland when he sat down with internet billionaire Kim Dotcom, then a relatively recent arrival to Auckland, having immigrated under the National government's new 'welcome mat for rich people' scheme. I've sat in the same chair where, as Dotcom tells it, Banks said that the $50,000 donation would be welcome, but it'd be even better if he split it into two cheques. Why? If a larger single cheque was received, "then he would not have to declare where it came from", Dotcom claims Banks said. And, Dotcom added, Banks said it would be easier for him to help if the donation was anonymous.

It's a damning story and it reflect badly on both men (a point not often made). Regardless of the law, Banks seems to have been trying to cheat the system and Dotcom was happy to go along, because he hoped to get something, at some point, in return for the donation.

In fact Dotcom did ask for something from Banks. A mattress. Dotcom found himself in prison after the raid on his mansion by our spy agencies and police and his back problem was playing up. His prison bed was causing immense pain, but the guards didn't care. He put in a call to Banks. And, as Dotcom tells it, Banks didn't want to know him. That hurt Dotcom; he felt betrayed. The rest is history. And now, it seems, is Banks' political career.

It's worth remembering the nub of this story, because beyond all the political point-scoring and the questions over anonymity is the principle of our electoral law. Those standing for office need to raise money. As part of that ambition they need to be able to ask people for donations. But the law requires those donations to be disclosed, as the 1986 Royal Commission on the Electoral System observed. It's a reason that Justice Heath took time to quote in his decision yesterday, which found that Banks will have to face trial next year.

"in the absence of disclosure ... there is no way of knowing whether or not a candidate’s financial position is likely to influence decisions taken if the candidate is elected, or whether the candidate is improperly accepting personal donations in exchange for promises of future action once elected". The statutory provisions dealing with the need for disclosure of donations must be read in that context.

Indeed it must.

Because the vital issue in this case is whether Dotcom was trying to buy Banks' favour with this donation and whether Banks accepted it with a nod and a wink in that direction. While the trial will be around the legal technicality of what Banks knew at the time he signed off the expenses return, the moral question is whether he was willing to owe someone a favour or two for the sake of a hefty campaign donation.

In this case I fear Banks may have just been the one who was sloppy enough to get caught. At very least, I'm sure other politicians ask for money, often know who's donating to them and who isn't, and then sign donations off as "anonymous". Presumably the proper process is to get someone else to give a potential donor a call and handle the money, whereas Banks did the talking himself never thinking it would leave the room.

I don't know how that will play out in court. As Heath said in his decision, much will depend on the trial itself. Banks may be entirely innocent before the law.

But his decision today to step down as ACT leader in March and not stand again in next year's election is a grudging admission that that's no longer relevent. In the court of public opinion he's been found guilty.

Voters have decided that regardless of the law, he knew Dotcom was donating a large sum of money to his campaign -- he asked for it, for crying out loud, then rang back to say thank you --- so it's contrary to Kiwi commonsense to then claim that the donation was "anonymous". Voters won't back him again and won't have time to forget when he's in court just months before the election, so he's political deadmeat.

It seems ACT members have made that clear to him, in the hope they can find someone without such damaging baggage to lead them into next year's election and -- they hope -- another deal with National. You've got to wonder whether ACT has someone lined up.

Frankly, it'll be a tough ask for anyone stepping into that role. If the quiet word has come from National that a deal is in the bag, it's the fast-track to a ministerial post, the leadership of a whole party and the minor parties' leaders' debate. But it's an increasingly insignificant party, and one who's time has passed. You'd be living entirely on the grace and favour of John Key, and there's no guarantee he'll have the power to hand out any favours come the end of next year. Would anyone of real ability and ambition want to take that deal? Who would want to try to rehabilitate that rag-worn brand?

After Brash's revolt, ACT had hoped Banks would be a safe pair of hands. But it's turned out his hands were dirty. A small party might have been able to survive one leadership snafu, but two seems incredibly hard to recover from.

For Banks, he'll have an uncomfortable summer, something Dotcom probably thinks is some sort of justice in its own right. You might say that John Banks has made his bed and now he has to lie in it.