Once designated, the local authority is then charged with paying "special attention" to the desirability of preserving or enhancing the character or appearance of the area. This apparently simple and straightforward statement has become a matter of real contention, frequently and widely debated. There are many "character and appearance combinations". A proposal to convert a run down residence to a nightclub, for example might not preserve the character of an area but could enhance its appearance. See the "Steinberg Principle".
Unlike listing, there is, in theory at least, no category of conservation area all are held to be of the same value, except in Scotland, where conservation areas can be declared to be "outstanding". This status is conferred by Historic Scotland and has the effect of making a variety of works in such areas for example, to unlisted buildings, eligible for grant aid.