Wouldn't we have had to sign up our agreement to the conditions of FFP at some stage in the past ?
No. These regulations were not enacted at the end of a democratic process which obtained the consent of clubs involved in the member leagues. If any clubs were consulted it was the G14. They objected to the original proposals which were concerned with the problem of debt to the extent that they threatened legal action. UEFA gave way and certain clubs were allowed considerable input into the formulation of the regulations which emerged and these dealt only with spending and not with debt (which wasn't mentioned). Clubs had been promised that the regulations would not prevent clubs doing anything which the law permitted and it is obvious that the regulations drove a steamroller over that commitment.
City have never "signed up" to these regulations but made it clear, I believe, that they would not contest them in court because the club's aim after 2008 was to enter a period of heavy investment to enable the club to compete at the highest level
from its own resources. Had City expressed opposition to the regs and/or gone to court the club would have been sanctioned and/or banned from the CL and legal action would have been very lengthy and UEFA knew this was a real deterrent. The length of the process explains why City agreed to take the "pinch" in 2014 despite their instinctive reaction being to contest the judgement. In 2014 the club's position was that it would not accept that it was guilty of any "wrongdoing" (a significant choice of word?) and that is still its position. So, the club has never been asked to sign up to, or accept, the rules and I think one very strong argument it has, though not perhaps in CAS, is that the rules are an imposition which violates the promise of protection of owners' legal rights, rules which were drawn up with undue heed to the demands of a small number of clubs which sought to protect their own interests
at the expense of those of other clubs and which have been used to hinder the progress
specifically of Manchester City.
This raises the question of the nature of the "shitstorm" if one actually exists. I suspect that it may well not be a battle fought out in the press but rather at more official levels and even in the courts because if City's appeal is upheld UEFA can't do anything to stop us and if our appeal is rejected we have nothing to lose. The storm would raise questions about prejudice, consistency and possible corruption and the material is plentiful and readily available. For example: why have UEFA shown no interest in where the money from Liverpool's money laundering sponsors actually comes from? Why was FFP "reformed" the year after City were sanctioned in 2014 to allow clubs to do exactly what City were sanctioned so heavily for? Why have UEFA failed to take action against Russian clubs which have flagrantly ignored the regulations? Is the latter connected with the world cup of 2018? What investigations have UEFA carried out into the handling of PSG's sponsorship deals by the IC, and in particular the role of M. Leterme in investigating them? Is the TV deal with Bein sports in any way connected with these matters? Could UEFA clarify the role of Qataris in UEFA's affairs? And so on. If City do have a black book on dodgy dealings at UEFA these and other matters could get really interesting, not to say embarrassing.
I think City is one of very few honest clubs in a den of crooks, but we are not the reactive pushovers some claim and I do think we are in for turbulent times in Switzerland whatever happens at CAS.