MailscanA legal opinion commissioned by George Osborne suggests that Gordon Brown’s doubling of air passenger duty may be unlawful and passengers can refuse to pay it (Daily Mail).  Mr Osborne said:

"The increase in air passenger duty is an additional tax that adds to the already high cost of living and the rising tax burden, and because of the way it has been introduced retrospectively the increase has caused confusion and may even be illegal.  Indeed the legal opinion we’ve received says there is no legal basis to collect the increase in tax."

British Airways has itself absorbed the cost of the increase but most airlines are attempting to force customers to bear the retrospective tax.