The annulment of planning permission means in principle that the permission is deemed never to have existed; however, if it appears that this retroactive effect of the annulment is likely to have manifestly excessive consequences because of the public interest that may attach to temporarily maintaining its effects, the administrative court must take into consideration, on the one hand, the consequences of the retroactivity of the annulment for the various public or private interests concerned and, on the other, the drawbacks that limiting the effects of the annulment in time would entail with regard to the principle of legality and the right of litigants to an effective remedy.