If we have courtroom imagery, and any kind of stand-in representative for the defendants, then there is no way for the thing to work without imputation.
Wright confuses things enormously when he rejects the idea that righteousness can float across the courtroom from the judge to the defendant. Of course it cannot, and defenders of imputation never claimed that it could. Because it cannot float from the judge to the defendant, in order for us to be justified, it was necessary for the Incarnation to happen. The judge needed to figure out a way to become a legitimate representative of the accused. He did not, as the judge, shoot righteousness rays across the courtroom. Rather He was born of a woman, born under the law.
And so contra Wright, the picture is more like this. Adam is in the dock, and lined up behind him (in the billions) are all his descendants, condemned because of his disobedience. He was a federal, covenantal head of the human race, and so his sin was reckoned to all of us, considered as ours, imputed to us. And so Jesus was born into our race as the last Adam, and the same kind of thing happened. Jesus stood in the dock, received the penalty that was due to Adam, rose from the dead, and was vindicated or justified by God. And so everyone who lines up behind Him is therefore justified as well. His payment of the penalty, and His perfect obedience in its own right, are now credited to us who believe in Jesus. The obedience of Jesus is imputed to us in just the same way that the disobedience of Adam was.
So the dots that have to be connected are not the dots between God as judge and Adam, or God as judge and Jesus. The dots that have to be connected, and can only be connected by means of imputation, are between Adam and his descendants, the elect descendants of Adam and Jesus, and the last Adam and His descendants. In short, there are three things that must be imputed — Adam’s disobedience to us, the penalty for Adam’s disobedience to Christ, and Christ’s obedience to us. Otherwise, however righteous Jesus is being, it is just someone else, over there, being righteous. It can only come to us by imputation.
So Wright says that he rejects imputation, and if he means judge-to-defendant transactions, I don’t blame him. But the kind of imputation that connects a perfect Adam to an imperfect people is the hope of the world, about which Wright writes so eloquently.