as you probably remember, I can see both sides of that situation.
I understand why STA went to court, but in doing so what they actually achieved IMO was to prolongue the period of uncertainty and negative publicity, as well as resulting in another mad rush of customers getting totally unjustified FIT returns, which IMO then led pretty much directly to the decision to cut the FIT again from 21p to 16p almost immediately. Now, I'll accept that the STA aren't directly responsible for all this, BUT it was blatantly obvious from the outset what the result would be in the medium term if they did take this legal action, and tbh I don't see that it's going to have had any sort of deterrent effect on DECC for the future, as they've demonstrated their ability to drag the legal proceedings out as long as they want to in order to further their aims of reducing the impact on the FIT budget.
The one good thing I will say about the action they took is that it confirmed that FIT changes can't be applied retrospectively.
They do also potentially clear the way for compensation claims, although any compo claims are going to be pretty divisive as they'll only benefit the firms with the funds and time to put into the legal action (if successful), thereby giving them a massive competitive advantage over everyone else, whereas the entire industry will pay for it, as it will no doubt come out of DECC's renewables support budget in some form or other, so no new money will enter the industry as a whole, it'll just be concentrated on a few firms with decent lawyers.