Birkenstocks may be cool enough for Barbie but the sandals do not qualify as works of art, a German court has ruled. The company had claimed its footwear could be classified as art and so was protected by copyright laws in a case it put forward to stop rivals selling copycat versions of the cork-soled sandals. But a judge dismissed the claim, saying the shoes were practical design items - a decision Birkenstock called a "missed opportunity for the protection of intellectual property". Birkenstocks' popularity means rivals often sell knock-off versions, prompting the firm to make the claim to protect what it called its "iconic design". In this case, Birkenstock took three manufacturers and retailers to court, seeking to protect four of its sandal designs. German law distinguishes between design and art when it comes to a product. Design serves a practical purpose, whereas works of art need to show a certain amount of individual creativity. Art is covered by copyright protection, which lasts for 70 years after the creator's death, whereas design protection lasts for 25 years from when the filing was made. Shoemaker Karl Birkenstock, born in the 1930s, is still alive. Since some of his sandals no longer enjoy design protection, the firm attempted to gain copyright protection by seeking to classify its footwear as art.