As an industry that attempts both to reflect and influence popular culture, advertising often finds itself treading a difficult line. Like any medium, its creative impetuses rarely exist in a vacuum - influence has to come from somewhere. Yet the industry's primary allegiance to commerce, not art, opens it up to a particularly bitter brand of criticism, when one of its ideas bears a resemblance to another.
The latest ad to be branded for "thievery" is Fallon's new "Play-Doh" spot for Sony Bravia. In a flurry of posts on online message forums, the ad, which featured animation by Passion Pictures, has been accused and convicted of plagiarising an illustration featuring rabbits frolicking in an anonymous US city, created by a pair of Los Angeles artists named kozyndan.
If the morally outraged messaging on kozyndan's Flickr page is any measure, "Play-Doh" is the latest example of an industry bereft of ethics, interested only in appropriating any work that helps it crack the brief and confident in the knowledge that the creators of the ideas it steals will be reluctant to take legal action and unlikely to win if they attempted to do so.
Such a damning view is, of course, reflective only of the level of fandom artists such as kozyndan enjoy. The reality is typically blurry - it's next to impossible to isolate the point at which inspiration tips into plagiarism, but that won't stop the industry being forced to raise its defences when the perennial "rip-off" row comes to town.
Certainly, the ad and the illustration bear striking similarities. More fat was added to the fire when kozyndan claimed in a post that "someone representing Passion Pictures contacted us almost two years ago asking to see samples of our work (including this panoramic), as they were interested in working with us. We sent them samples and then heard nothing from them ever again."
Fallon is understandably reluctant to be drawn into a debate rendered redundant by the sheer number of times it has been held. However, a source close to the Sony account at the agency defended the animation company, saying: "Passion Pictures is being held up as part of this so-called 'rip-off', based on the fact that it contacted kozyndan two years ago. What Passion Pictures did in the making of 'Play-Doh' was purely to execute an idea that had been locked down at least six weeks before it was involved; it had no influence whatsoever. It's a pure coincidence."
As is the US location and the preponderance of rabbits. According to the source, the original plan was to film the spot in St Mark's Square in Venice, and to use a multitude of creatures - not just rabbits.
Whether or not Fallon knew of kozyndan's work, the level of outrage surrounding "Play-Doh" is fuelled, in part, by an industry which has borrowed heavily in the past, and has been bad at acknowledging, let alone repaying, its debts.
One of the highest-profile cases in recent memory concerned the award-winning "cog" spot, created by Wieden & Kennedy for Honda.
The famous chain-reaction ad bears more than a passing similarity to the 30-minute film Der Lauf Der Dinge (The Way Things Go), created in 1987 by the Swiss artists Peter Fischli and David Weiss.
The W&K creatives Ben Walker and Matt Gooden admitted they had "copied" one element from the film - a shot in which weighted tyres roll uphill. Walker later said that he regretted doing so, and the ensuing criticism was blamed for the ad failing to win the Grand Prix at the Cannes Lions in 2004. Does he still feel that way now?
"I don't regret anything about the project at all," Walker says. "I was just trying to appease the angry mob. We didn't want to copy Der Lauf Der Dinge, we felt inspired by it. The bit with the wheels seemed natural to borrow, at the time. It was so beautifully simple, far too clever for us to have conceived. In retrospect, we should have just thought of something else to do with wheels, but to say I regretted it is me lying, again."
It's easy to argue "cog" is inspired by, rather than copies, the film it resembles. The Turner Prize-winning artist Gillian Wearing was less chuffed when BMP DDB based a 1997 Volkswagen campaign on her 1992 Signs That Say What You Want Them To Say and Not Signs That Say What Someone Else Wants You To Say work.
Wearing sought legal advice, but ultimately chose not to pursue the matter in court. Perhaps she was deterred by Mehdi Norowzian's case against the Irish agency Ark, which, he claimed, had based its Guinness "mambo" spot on his film Joy. The courts didn't agree. Norowzian lost and had to pay an estimated £200,000 in legal costs.
Under British law, proving that an advertising agency has breached copyright or is attempting to "pass off" a campaign as the work of an artist is legendarily difficult.
"Copyright covers the expression of the idea, not the idea itself," Brinsley Dresden, of the law firm Lewis Silkin, explains. Which means that although the underlying idea may be similar - rabbits in a cityscape, tyres rolling uphill, members of the public holding signs - as long as they differ executionally, no copyright has been breached.
Passing off, whereby an artist attempts to prove that a brand is attempting to cash in on their goodwill or reputation, is another option - it worked for the British installation artist Andy Goldsworthy, who received £70,000 in an out-of-court settlement in 2002 from Habitat's then ad agency devarrieuxvillaret after claiming that its campaign for the furniture chain copied his Midsummer Snowballs installation.
Wearing, like Goldsworthy, was concerned that viewers would assume she was behind the camera on the VW campaign. When Ogilvy approached her in 2002 with a request to use a short film in which children and adults swapped voices, they invited her to make the ad for them. Mother did the same with the film-maker and artist Alison Jackson when the agency used her behind-the-scenes celebrity footage as an idea for a Schweppes ad.
While kozyndan still maintain that Fallon's inspiration is "blatant", the thread on their Flickr site concludes with the duo conceding the agency "used our work as a starting point and took it to a whole other place. We would certainly not want to take away from the hard work of all people involved in the production of this piece, because we actually really like the ad.
"It would be nice if the ad agency responsible for concepting it would acknowledge where the inspiration came from, though."
Walker agrees that inspiration should be acknowledged. "To take what someone has done and change it, to move it on, is to be inspired by something. To lift what someone else has done and stick your product at the end is copying. The Bravia ad certainly takes the original in a new direction. This is the key - it doesn't feel cynical," he says.