A bill of £100,000 or more could land with the council if it continues to contest Stansted Airport's expansion plans.
Councillors will vote tonight (October 6) on whether to appeal a High Court ruling that Stansted Airport can expand to accommodate eight million extra passengers each year.
High Court judge Mrs Justice Lang DBE ruled the court will not hear a council proposal to throw out the plans, declaring UDC's grounds "unarguable" last week.
A report by the newly appointed chief executive Peter Holt warns that costs could be difficult to control if the council decides to appeal the judge's decision.
If the court agrees to a full hearing, the process could cost taxpayers an extra £100,000 or more.
The report notes that UDC could spend more than £1.5 million on the case in total.
Mr Holt's report reads: "The decision that council must make is a matter of political judgement.
"Are members prepared to incur the certainty of escalating costs set against your analysis of the likelihood of an ultimately successful outcome on the actual planning matter at the heart of these legal processes?"
UDC's Planning Committee previously refused permission for Stansted Airport to build infrastructure which would increase its capacity by eight million passengers each year.
The government's Planning Inspectorate overturned this decision and said the airport's operator - Manchester Airport Group - could claim costs against the council.
Stansted Airport claimed £50,717.50 against UDC.
The High Court ruled this figure was too high and reduced the sum to £15,000.
A spokesperson for Residents for Uttlesford, the UDC ruling party, said: "By allowing yet more huge increases in carbon emissions rather than reductions, the government has shown a very serious dereliction of duty."
Councillor Chris Criscione, Conservative group leader, said: "This administration tried playing politics with the planning system, bodged their attempt and now look to blame anyone but themselves for their failure."
Cllr Melvin Caton, Liberal Democrat group leader, said: "I am certain that when people voted for R4U in 2019 they did not expect to end up with the worst of all worlds - an expanded airport and costs approaching £2 million."
An earlier version of this article noted that a Statutory Planning Review is the next stage of the planning process. This is incorrect - the High Court has dismissed the council's application to hold a Statutory Planning Review, which the council could appeal.
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