Those who can, create. Those who can't, copy

Ok Go's video won a Grammy and is an elaborately choreographed, fixed-camera, single-take masterpiece. The Berocca advert cuts between a dissolving tablet and people rising from tables to dance on running machines in a city centre. The songs are different but, in what may become the world's first legal dispute over treadmill dancing, an issue of copyright infringement could be determined by comparison of the videos' individual dance moves.

A source close to the band claims: "There was extensive negotiation to use Ok Go (by the JWT advertising agency on behalf of Berocca's manufacturer Bayer] but this didn't bear fruit." The source says JWT had no authorisation to reproduce the choreography. JWT and Bayer have, thus far, ignored all requests for a statement.

This Saturday is World Intellectual Property Day. It is also a week since JK Rowling began an action in New York against the Harry Potter Lexicon, claiming that the encyclopaedia infringed copyright by taking material from her novels, and that publication would "open the floodgates" for countless publishing rip-offs.

In March, an advert for Sugar Puffs angered fans of The Mighty Boosh when it seemed to show the Honey Monster crimping in the style of comedy duo Julian Barratt and Noel Fielding. A "crimp" is perhaps best described as a staccato rap.

The Boosh's management company, PBJ, has issued a complaint to the Advertising Standards Agency and Barratt and Fielding performed a derogatory crimp at the Honey Monster's expense on BBC3's recent Mighty Boosh Night.

Father Ted and The IT Crowd writer-director Graham Linehan empathises. He and Arthur Mathews, co-creators of the BBC sketch show Big Train, contemplated suing over adverts for Sony PlayStation 2 that they felt infringed copyright of their most celebrated sketch; a spoof wildlife sequence showing jockeys in the African savannah being hunted by The Artist Formerly Known as Prince (that name itself part of a notorious intellectual property case). The PlayStation commercials featured various "herds" of jockeys, golfers and ventriloquist dummies in a safari setting.

"We were told it was a win-win situation for advertisers if you sue because it brings attention to them and their product," Linehan explains. "And theirs was so badly done and unfunny we thought it wouldn't be remembered.

"I've done a few ads myself, worked with some nice creatives, and they always seemed original. But there are a lot who simply watch telly, go to art shows and write down things to steal. After I made Big Train, advertisers would ask if I wanted to direct an ad. I'd see their sketch and it would be very Big Train, so I would automatically say no. Then, a few minutes later, they would phone back and ask for a tape of the show, so they could use it as a visual aid to rip me off!"

Under the Copyright, Designs and Patents Act 1988, the crucial judgment to be established is whether a "substantial part" of the original work has been reproduced.

In 1998, film director Medhi Norowzian launched an unsuccessful lawsuit against Guinness and the Irish advertising agency Arks over the commercial Anticipation, which featured actor Joe McKinney dancing in expectation of a pint to the tune of Guaglione by Perez Prado. Norowzian had previously submitted a showreel to Arks that included the short film Joy, which showed a man performing an exuberant dance on a rooftop. Arks submitted a script and storyboard based upon the film to Guinness and Norowzian was approached to direct. Unwilling to "commercialise" an existing idea, he refused and a new director was instructed to create something "with an atmosphere broadly similar to that portrayed in Joy".

Norowzian lost his appeal against a High Court decision dismissing his copyright infringement claim, because the court decided that the film, not the dance, was the original work and Anticipation's jump-cut editing made it substantially different.

"The important distinction," explains Colin Hulme, a partner in the intellectual property and technology team of law firm Burness LLP, "is that copyright only protects the expression of the idea, not the idea itself.

"The courts don't look at the quantity, the amount of work taken, but the quality of what's taken. For example, the opening bars of a famous song might comprise a substantial part because they could be enough to identify the track.

"If a substantial part of the dance moves in a video were copied in another video that could well be copyright infringement. This was looked at in the Guinness advert and there was very close discussion of the similarity of the moves. But it was decided that what made it exciting was the chopping of the footage, the editing."

Hulme stresses that "this is a very complex area of law, but it is fairly well settled. Difficulties arise because technology is changing and the law isn't keeping up, especially in regulating the transfer of intellectual property over the internet."

Most people have never heard of Joel Veitch. But there is a good chance you may know his work from television and viral advertising on the internet.

"Obviously, I didn't invent singing animals, so it's difficult to explain what makes my animations distinct," the director says of creations that include the singing kittens on the current Crusha milkshake adverts and singing penguins for Switch/Maestro.

In January last year, Veitch reached a settlement with Coca-Cola after an advert appeared in Argentina that used his unsigned band 7 Seconds of Love's song Ninja and a video full of kittens. Dangerous, released this summer. Veitch himself was once threatened with a lawsuit by Gullane Entertainment Inc for uploading a parody of Thomas the Tank Engine to his website.

"They were actually very nice about it because it was horrible," he recalls. "They sent me a letter saying, 'Look, this is our intellectual property, it is a children's thing and we understand this is parody. But it is really inappropriate, so we want you to remove it.' Which was fair enough, and I did.

"Interestingly, it was made before I started doing this professionally. A lot of artistic content on the internet is not commercially made, a million music tracks and photos used without permission, with no justification under IP law. But no-one worries about it because you'd be crazy to pursue it legally.

"The flip side is that while nothing exists in a creative vacuum, there has been a perception that if something is on the internet it is somehow in the public domain and you've relinquished your rights to it. The media always moves quicker than legislation."

Proof of this comes in the form of 18-year-old Nick Haley, who created his own advert for Apple's iPod and posted it on YouTube. Instead of suing the British student for infringing their intellectual property, publicity shrewd Apple bought the rights to his ad, (which, presumably, they already owned) and faithfully reshot it, broadcasting it on US television.

With websites such as youthoughtwewouldntnotice.com, the internet has also become a protest forum for artists who believe they've been plagiarised.

"When you are talking about individual artists up against multinational brands, it is not a fair fight, the law is almost inaccessible," claims Veitch. "In practice, it is very much weighted for the benefit of those who can afford lawyers and risk going to court.

"But if you are a popular artist, you can mobilise a groundswell of support in your favour via the net in a way that you could not before. It is possible to stamp your feet and make enough noise to get attention."