Four Bristol taxi drivers are taking court action to try to stop the council forcing them to paint their cabs blue.
The City Council wants all the taxis it licenses to be the same colour to make it easier for users to recognise them.
Two years ago the authority announced all of its 780 Hackney Carriages had to be painted blue by May 2011.
But the drivers argue respraying the cabs costs between £1,500 and £4,000 and that they were not properly consulted about the scheme.
The case will be heard at Bristol Magistrates' Court on Wednesday.
A spokesman for the City Council said the colour was being introduced so people knew they were hailing a genuine licensed taxi cab.
He also said that a blue plastic covering would be an acceptable and cheaper than a full respray.