Council Directive 1999/74/EC (July 1999) made a distinction between 3 types of rearing systems for laying hens. Of these, the non-enriched cage systems have been prohibited since 1 January 2012. The systems which remain in use are:
enriched cages where laying hens have at least 750 cm² of cage area per hen
alternative systems where the stocking density does not exceed 9 laying hens per m² usable area, with at least one nest for every 7 hens and adequate perches
Whichever system is used, all hens must have a nest, perching space, litter to allow pecking and scratching and unrestricted access to a feed trough.
The directive also states that all egg production units must be registered with the competent authorities in EU countries and have a distinguishing number which can be used to trace eggs back to their farm of origin.
For full details please refer to the directive.