The K2 tax-avoidance scheme Carr is said to have used enabled members to pay income tax rates as low as 1%.

BBC: Tax avoiders should be named and shamed, says watchdog

For decades, the Internal Revenue Service has asked courts to look past the fancy lawyering and examine the substance of a tax-avoidance scheme.

FORBES: Tax Case Asks Whether IRS Flip-Flopped On Key Position

Allow HM Revenue and Customs to declare any scheme designed purely to allow the avoidance of tax "null and void" in law.

BBC: Bill-by-bill: Guide to MPs' private members' bills