EasyJet claims Gatwick charges hike unlawful
The low-cost carrier said the ruling would cost it 46 million pounds ($64.6 million) in extra fees over five years.
The claims emerged on Tuesday at the start of a high court battle between EasyJet and the CAA, which regulates Britain's airports network.
The case is likely to run for the rest of the week, with a ruling expected within two months. A CAA spokesman said the regulator would "vigorously defend our decision", referring to the original ruling on prices in March 2008.