Council lawyers were not asked for help when a new service for children with severe learning difficulties was started.
Jonathan Vernon-Hunt, a member of Brighton and Hove City Council's legal services team, told an inquiry into the Palmeira House affair that ideally a service should not be started without a signed contract.
But he said there was an urgent need to get the project going because of the children involved.
No contract was ever signed between the council and NCH Action for Children, which ran the project in Hove.
Eventually the two partners fell out over the rising costs of the project and a decision was taken to stop it.
But parents challenged the decision in the High Court and last year it was agreed to keep it going until all the children are adult.
Mr Vernon-Hunt told a scrutiny panel at Hove Town Hall: "I think social care and health were trying to get it sorted with NCH and saw no need to enlist our help.
"They knew how busy we were and probably thought it wasn't a legal problem."
He checked his records and discovered that for the whole of 1999 he had not been advised of any difficulty, saying: "It was not being put to me as a serious problem."
Mr Vernon-Hunt said things started to go wrong in 2000.
A report to councillors at that time did not do the job properly, which led to problems in the High Court.
Questioned by councillors, Mr Vernon-Hunt said it was not unusual for several lawyers to have been involved with a project because they had many other calls on their time.
At one stage there were three lawyers dealing with the previous project, called Marina House, within eight months.
The on-going inquiry was adjourned.
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