Walter Sofronoff KC had challenged a March report by the ACT corruption watchdog which said the former judge engaged in serious corrupt conduct.
That legal application was denied by Justice Wendy Abraham on Thursday.
"The applicant has not established that the finding of serious corrupt conduct is either unreasonable, irrational and/or illogical," the Federal Court judge wrote in her decision.
She found Mr Sofronoff had breached his non-disclosure obligations by releasing material relating to the report before it had been considered by ACT Chief Minister Andrew Barr.
Findings that the ex-judge exhibited a lack of honesty, good faith and impartiality, and had breached the public's trust through the leaks, were upheld.
Mr Sofronoff's claims he acted within his responsibilities as head of the inquiry were rejected by the Federal Court which found he did not have an unfettered discretion to do whatever he considered necessary.
Justice Abraham will now consider who pays the legal costs of the failed lawsuit.
At a hearing in July, Mr Sofronoff's barrister told the court his client was not corrupt but genuinely believed he was acting in the public interest by sending material such as witness statements to the media.
Lawyers for the ACT Integrity Commission backed its findings, saying the retired judge had threatened public confidence in the integrity of the government and public administration.
Mr Sofronoff chaired a board of inquiry into the ACT's criminal justice system after Lehrmann's controversy-plagued prosecution.
The former Liberal staffer was accused of raping then-colleague Brittany Higgins at Parliament House in 2019.
His criminal trial in 2022 was abandoned without a verdict because of juror misconduct.
Lehrmann lost a defamation lawsuit and a further legal appeal he brought over media reporting of Ms Higgins' allegations.
He has said he will take the case to the High Court.
The Sofronoff-led inquiry found the ACT's top prosecutor, Shane Drumgold, had lost objectivity over the Lehrmann case and knowingly lied about a note of his meeting with broadcaster Lisa Wilkinson.
Mr Drumgold resigned and launched his own failed legal challenge to the findings in the ACT Supreme Court.
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