"Mr Banks has had a distinguished career in both central and local government and I acknowledge the distress this matter has caused his family and him," Mr Finlayson said.
"I am, however, satisfied that Crown Law's supervision of the litigation was satisfactory and in line with the Prosecution Guidelines 2013."
Mr Banks was highly critical of Crown prosecutor Paul Dacre, QC and Solicitor-General Mike Heron, QC, after his acquittal, saying they had "a lot to answer for".
At the time, the Court of Appeal had ruled that Crown Law had misled the court by withholding evidence.
Mr Finlayson, who is the minister responsible for the Crown Law Office, gave his full support to Mr Heron.
"Because of the personalised nature of some of the allegations about the conduct of the Solicitor-General, I state for the record that he has my full confidence. He is an outstanding Solicitor-General," he said.
The Crown took over the case from serial litigant Graham McCready, who took a private prosecution against Mr Banks in relation to donations he received from Kim Dotcom during his mayoral campaign in 2010.
Crown Law briefed an independent barrister for the case because it was politically sensitive and because Mr Dotcom, who is facing extradition to the United States, was a witness in the trial.
Mr Finlayson said the next step in the case would be determining costs, which he said was a matter for Crown Law and Mr Banks' lawyer.
"I will be making no further comments," he said.
