WESTMINSTER City Council's policy of selling off housing stock was "judge-proof" after it was given the go-ahead by Jeremy Sullivan QC, the inquiry heard on its final day.
Anthony Scrivener QC, acting for former council leader Dame Shirley Porter, said the District Auditor John Magill had been wrong to declare the scheme unlawful.
Scrivener, who noted that the inquiry had lasted longer than World War II and had been the most expensive audit in UK history, said no one had ever been surcharged for following legal advice.
He added that Magill had misinterpreted the law by relying on the wrong legal precedent when coming to his provisional conclusions.
The auditor will mull over defence submissions before deciding in the summer whether to stick with his original view that councillors and officers were guilty of trying to fix the elections by luring Tory voters into marginal wards.
One of the officers accused of being involved in the alleged gerrymandering is Westminster's former deputy solicitor Robert Lewis, now an environmental law partner at Freshfields.
If the auditor refuses to change his view on Lewis and his co-accused, he will have to apply to the High Court to surcharge the six councillors and four officers.