"These are completely artificial transactions," said Kurt Wulff, an energy analyst at McDep Associates in Boston.

The I.R.S subsequently denied the trading losses, saying that they were artificial transactions that amounted to an abusive tax shelter known as Son of Boss.

In Street v Mountford it would have been more accurate and less liable to give rise to misunderstandings if the word 'pretence' had been substituted for the references to 'sham devices' and 'artificial transactions' (post, p. 462H).