157The finding of illegality made by the court does not have erga omnes effect, but entails the illegality of the individual contested decision, whilst leaving the act of general application in the legal order without affecting the legality of other acts which have been adopted pursuant thereto and which were not challenged within the period for appeal (see, to that effect, judgment of 21 February 1974, Kortner and Others v Council and Others, 15/73 to 33/73, 52/73, 53/73, 57/73 to 109/73, 116/73, 117/73, 123/73, 132/73 and 135/73 to 137/73, EU:C:1974:16, paragraphs 37 and 38).