Council Directive 2008/119/EC of 18 December 2008 laying down minimum standards for the protection of calves.
1. From 1 January 1998, the following provisions shall apply on all newly built or rebuilt holdings and on all those brought into use after that date:
(a) no calf shall be confined in an individual pen after the age of eight weeks, unless a veterinarian certifies that its health or behaviour requires it to be isolated in order to receive treatment. The width of any individual pen for a calf shall be at least equal to the height of the calf at the withers, measured in the standing position, and the length shall be at least equal to the body length of the calf, measured from the tip of the nose to the caudal edge of the tuber ischii (pin bone), multiplied by 1.1. Individual pens for calves (except those for isolating sick animals) must not have solid walls, but perforated walls which allow the calves to have direct visual and tactile contact.