This is a very disappointing decision, as the consumer problem which BT alleged it was seeking to address will actually be properly resolved when (if?) the new Ofcom measures come into effect in June next year.
It is further disappointing as the behaviour of the Supreme Court, in overturning an Ofcom determination, may offer comfort to those who have been threatening to take legal action to prevent Ofcom's measures being implemented. This consideration is made more relevant by the fact that the largest potential loser from this decision is the party who was threatening to itself take action to stop Ofcom.
This particular issue was always very ugly and things may now get worse. We will have to watch for developments.
(P.S. Many thanks to bigjohn for spotting this news and drawing it to our attention - Ofcom failed to make any announcement about this development when it occurred on 9 July 2014. The relevant case -
cw_01083 - was actually closed on 13 August 2013, with the determination that has now been finally overturned, after having previously toggled back and forth through the Competition Appeals Tribunal and the Court of Appeal.)