Cities and communes in Poland run electronic ID programs for animals, based on the Cleanliness and Order Act dated 13 Sept 1996 (Dz. U. from 1996. No. 132, item 622, amended.). The act is available in the attachment.
There is also a directive of the European Parliament and Council of Europe no. 998/2003 along with the European Commission ruling of 26 Nov 2003.