The Supreme Court has delivered a mixed ruling in the battle between George Lucas's movie empire and a UK prop designer over the sale of the iconic Stormtrooper helmets from the Star Wars films.

The Court held that while Lucasfilm can enforce a US copyright in the UK, the Stormtrooper helmets sold were functional, rather than works of art, and therefore the defendant did not breach copyright laws.

The US film production company had attempted to stop Twickenham-based designer Andrew Ainsworth from selling replica costumes over the internet – both in the US and in the UK. Lower UK courts had ruled in 2008 and 2009 that the costumes were not works of art and therefore not covered by British copyright law.

The Supreme Court today (27 July) upheld these decisions, while simultaneously conceding that Ainsworth had violated Lucas's copyright in the US by selling costumes there, and that he should be forbidden from doing so in future.

The Supreme Court also concluded that, provided there is a basis for 'in personam' jurisdiction over the defendant, an English court can exercise jurisdiction in a claim against persons domiciled in England for infringements committed outside the European Union.

Mayer Brown London litigation chief David Allen commented: "The judgment means that the UK will become a destination jurisdiction for forum-shoppers keen to find the best jurisdiction for hearing and, critically, enforcing IP disputes wherever infringement has taken place – particularly, for example, where infringement takes place in a country with less stable and internationally respected legal systems than the UK, such as the third world."

Allen & Overy intellectual property (IP) partner Huw Evans added: "Even though the Imperial Stormtrooper helmets were the product of much imagination and creativity, the Court still viewed them as functional items within the context of the film and denied them the full copyright protection which would have given them a much longer period of protection for their merchandising around these helmets."

He added: "In essence the Court held that it was the film which is the artistic work and not the helmet. It follows that full copyright protection for 3D articles in the UK will generally continue to be limited to the fine arts."

Linklaters IP partner Nigel Jones added: "Businesses should heed the Court's warning that the boundaries of copyright protection should not be extended to works which do not fall within its intended ambit. It was on the basis of this point of principle that the Court held that the Imperial Stormtrooper helmets should not be treated as sculptures, and as a result, not qualify for copyright protection under English law."

The case saw Lucasfilm instruct Harbottle & Lewis IP partner Mark Owen, who in turn instructed Brick Court Chambers' Jonathan Sumption QC to lead the advocacy alongside Wilberforce Chambers heavyweight Michael Bloch QC. Ainsworth was advised by West End-based firm SC Andrew, which instructed Alastair Wilson QC of Hogarth Chambers.