Dublin City Council may face legal costs of €2 million following a High Court judgment.
The judgment, received by the council this week, came after 40 days in the High Court for developer Jerry Beades.
Mr Beades took an action against the council arising from its handling of two planning applications made by his company, Jerry Beades Construction Ltd, in 1993 and 1994.
Mr Beades had applied for retention of work done to his property at Hardwicke Place in the city centre, but was refused permission by the council and subsequently by An Bord Pleanála. He alleged his case had been prejudged by the planner handling it.
A note was subsequently brought in evidence signed by the planner, in which he said the recommendation would be to refuse the retention application. However, the note was written four months before the application was received.
Mr Justice William McKechnie ruled that he was satisfied the letter was a declared position on the issue.
"If a planning authority could legitimately have the view, as expressed in the note, at a time when a planning retention application had not even been submitted, there would in fact be no point in this statutory entitlement. This constitutes evidence of prejudgment," he said.
In his 65-page judgment, the judge said Mr Beades had contacted senior planner Michael Gough about his concerns. Mr Gough had promised to deal with the retention application personally, but his report was removed from the planning file by a person who has never been identified.
The judge fully absolved Mr Gough, who, he said, made the entirely correct decision to deal with the application himself.
He also found there had been shortcomings in how Mr Beades' complaints were dealt with and serious omissions "along the lines of command and responsibility".
He said the decision by assistant city manager Derek Brady to ratify the decision on the planning application was based on "an incomplete and screwed version of the true circumstances".
He ruled that the retention application was not considered fairly or impartially or on its merits, and involved a breach of natural and constitutional justice.
He also criticised the council's decision not to disclose details of an internal inquiry in 1995, until the fourth day of the trial.
Mr Beades said he was happy with the judgment and would consider taking an action for damages. He may also request the Minister for Justice to hold an inquiry.
A spokeswoman for Dublin City Council said the judgment was being examined to decide what action if any should be taken, including the possibility of an appeal to the Supreme Court.
