The incinerator project was put under the legal spotlight after the High Court granted an urgent hearing for a case filed by the Lewes District Friends of the Earth.
But the court ruled the planning process was sound.
Councillor Eddie Collict,
who is against the scheme, spoke after the decision was made last week.
Cllr Collict said, "I'm obviously disappointed.
"It shows that the legal system is not about justice but about law.
"How can it be right when there is widespread objection to it? It can't be right to force it on people."
While last week's hearing was going ahead campaigners made their feelings clear after several broke into the site of the proposed incinerator site at the North Quay, locking themselves to equipment and climbing the boom of the crane.
A total of 11 people have been charged with aggravated trespass and a 45-year-old woman arrested for allegedly causing an obstruction and assaulting police has been bailed.
Cllr Collict added that in the main most people had acted in a civil manner and praised those that had done so. He said, "I do think that it's a great credit to people that have fought this long.
"I think the strong feeling will continue.
"We are going to be landed with this thing for 30 odd years at least, we have to live with it for a length of time.
"Local people have been first class, the fact they failed is not a reflection on them but the stupidity of the county council."
Seaford MP Norman Baker added, "The law allows the county council to be judge and jury on its own application.
"The county council is railroading this through against the local population.
"It's not surprising, although I don't condone it, that some people have been protesting in the way they have."
Campaigners were victorious when the incinerator's pollution permit was quashed by the High Court last year in a separate legal challenge and remained hopeful that they would receive another positive outcome.
After the hearing Phil Michaels, head of legal at Friends of the Earth, said the organisation would be considering the court's judgement before deciding whether there were grounds to appeal.
East Sussex County Council said it was pleased with the outcome and would work with waste management company Veolia to continue with their plans to build the incinerator.
A spokesperson said, "We are very pleased with the result of the review of our planning procedures.
"We fully understand the concerns of people affected by this issue.
"Part of our job now is to reassure anyone who is worried that this is a safe and responsible option that will bring great benefits to the people of East Sussex, Brighton and Hove."
In a press release the council added that its priorities remain to reduce, reuse and recycle before energy recovery and landfill.
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