Green councillor Keith Taylor has been cleared of giving confidential information about the expansion of Shoreham airport to the press.
The Brighton and Hove City councillor, who holds one of the few hopes of the Greens' first seat in the Commons at the General Election, faced a five-year ban after a complaint to the Standards Board.
It was made after Coun Taylor, who represents St Peter's and North Laine, Brighton, stormed out of a confidential meeting and spoke publicly against plans to expand the airport.
The Standards Board ruled he did not breach any confidentiality rules.
Coun Taylor, said: "As soon as I realised runway expansion was the only thing this new owners' group was championing, I knew I was wasting my time trying to convince them they are making a big mistake.
"I am very pleased the Standards Board have put the allegations against me where they belong - in the dustbin.
"I'm very disappointed tax-payers' money has been wasted in this way.
"Each complaint the Standards Board hears costs an average £5,000. That's money down the drain, thanks to an allegation that I've said all along was groundless."
Green convenor Coun Taylor, who is standing for Brighton Pavilion, claimed the decision to call for an investigation into his conduct was politically motivated, a claim staunchly denied by Labour rivals.
An ethical standards officer from the Standards Board investigated the claim that he breached strict confidentiality rules.
The allegations were by Labour councillor Don Turner, chairman of the airport management committee.
Coun Taylor claimed the complaint was an attempt to gag him and said he asked for an apology from Coun Turner.
He added: "It was a waste of money and bad judgement."
Coun Turner is chairman of housing and chairman of the housing management sub committee as well as airport committee chairman.
Coun Taylor said: "The Standards Board is currently consulting on the way they operate and the Greens will be calling for a filter review to be available at a local level before complaints are formally lodged.
"If such a system had already been in place it is highly unlikely this complaint would have reached national level.
"The key issue of whether Shoreham airport should be enlarged to take bigger jets and 500,000 passengers remains.
"I will be putting renewed efforts to stand alongside the community to oppose this unwelcome and unwanted proposal and seek more sustainable and less damaging uses for the land."
The Argus was unable to contact Coun Turner last night.
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