Crocs, the manufacturer of a range of plastic clogs, has lost a battle to protect its design from copycats.

Judges in Luxembourg backed a decision by the EU’s intellectual property office (EUIPO) in 2016 to cancel legal protection for the shoe.

The European court of justice agreed that as the clog had made its debut at a boat show in Florida in 2002 and had featured on the company’s website, Crocs was too late when it sought its patent in 2004.

Under EU rules, protection cannot be provided if a design has been released to the public more than 12 months before an application is made.

A French retailer made representations to the EUIPO in 2013 arguing that the Crocs design should not be protected. The ECJ ruling agreed that anyone in the EU could have accessed the design.

“This judgment should serve as a useful reminder to designers to think about design protection early,” said John Coldham, a director at the law firm Gowling WLG.

Crocs, which has sold 300m units globally and whose shoes have been worn by the likes of George W Bush and Michelle Obama, has two months to appeal, but has not yet indicated whether it intends to do so.

The brand has both enthusiastic adherents and vehement critics. When Prince George was photographed wearing navy blue Crocs in 2015, sales on Amazon soared by 1,500%. Yet in 2010 Time magazine named Crocs one of the world’s 50 worst inventions.

“It doesn’t matter how popular they are, they’re pretty ugly,” the magazine claimed.

Websites about the design include Ihatecrocs.com and a Facebook group called I Don’t Care How Comfortable Crocs Are, You Look Like a Dumbass.