The Habitats Directive 92/43/EEC.

An the Joint Nature Conservancy Committe website has a good introduction to the Habitats Directive or you can view the full text and Annexes.

In the UK the Habitats Directive is made law through the Conservation (Natural habitats, & c.) Regulations 1994.

The Conservation (Natural habitats, & c,) Regulations 1994

Often known simply as the Habitat Regulations, this European law places a duty on the UK to designate key wildlife habitats as Special Areas of Conservation (SAC's) and makes it an offence to deliberately capture, kill, disturb, or trade in the animals listed in Schedule 2, or pick, collect, cut, uproot, destroy, or trade in the plants listed in Schedule 4. These actions can be made lawful through the granting of licenses by the appropriate authorities, in Wales the Welsh Assembly Government. Licenses may be granted for a number of purposes (such as science and education, conservation, preserving public health and safety), but only after the appropriate authority is satisfied that there are no satisfactory alternatives and that such actions will have no detrimental effect on wild population of the species concerned.

Following some court rulings, the Habitat Regulations have been amended in 2007. Defra has produced a guide to the habitat regulations ammendments.