How to assure security: CEN standards, directives, or European Guidelines?

It is argued, that to assure security, we need to make use of all three vehicles mentioned in the title, provided we select carefully which type to use in what circumstances. Many useful activities in these areas are under way. There is an important danger, however: if we do not take into account the needs of practical applicability, the net result of all efforts might be an increase of the gap between theory and practice, and thus a contrary effect of the intended one.