'I can spray a big red circle across the window and make it like a stop sign,' he said, his cheeks blazing a bright crimson in the August heat. 'And maybe I can spray black all over the logo.'

ROTH'S ANTIPATHY towards Cartier seems genuine enough but it is at odds with another aspect of his life. Along with other artists, Roth features in a groundbreaking graffiti exhibition that will run at the Cartier Foundation in Paris, France, until January 10.

The show, titled 'Born in the Streets', explores the emergence of graffiti and associated forms of street art in New York from the early 1970s, when spray paint became the most visible symbol of the city's slide towards anarchy. That era created a clich?of the rabble-rousing street artist, the city kid with a baseball cap on backwards and a spray can in hand; a disenfranchised youth always ready to risk imprisonment in the cause of art.

Roth, who was born in Okemos, a small town in the US state of Michigan, and developed his work on the tough streets of New York's lower east side, fits the clich?and the angry-looking ginger beard that punctuates his sharp chin suggests a pinch of substance, even if he is wearing short trousers.

The problem he has, especially as the wine kicks in and his emotion builds, is that Cartier, which funds its foundation through a trust that was initiated in 1984 by Alain Dominique Perrin, the company's former president, is happy for Roth to assault its windows with spray paint. The public relations people in Hong Kong have said so. And that gets under Roth's skin, as it should for any guy who claims that his name pops up either first or second (his ambition is unambiguous possession of top spot) whenever anybody searches Google with the phrase 'bad ass mother f***er'.

'It's a very cool idea,' he says, referring to the suggestion that he be photographed as he sprays Cartier's frontage to provide a cover image for this story. 'It's just that I don't want to make it seem like this is a collaboration between myself and Cartier. Like I'm endorsing them or something. That would be wrong.'

And yet in Paris, Roth has been the beneficiary of a very substantial piece of Cartier largesse. Along with Basco Vazko, Jonone, Richard 'Seen' Mirando, Delta, Cripta, Part One and P.H.A.S.E 2, graffiti artists who have worked outside the law for most of their careers, Roth was given the space and money to create a work specifically for the 'Born in the Streets' exhibition.

'It was a good opportunity,' says Roth. 'Of course, artists need to get paid. But I wasn't given any guidelines and I didn't know the Cartier in the foundation was the same one that makes jewellery.'

The 33-year-old is more like an archaeologist of graffiti than a practitioner. For the past few years, he has led a series of research projects on the subject, including co-founding the Graffiti Research Lab. His best-known project is the ongoing Graffiti Taxonomy (Hong Kong artists have been the most recent participants), in which he isolates characters from a collection of graffiti tags. Tags are the distinctive signatures graffiti artists (or 'writers', to give them their preferred name) embody in their work to ensure they are recognised.

Roth's work makes him like a modern-day Jean-Francois Champollion, the 19th-century philologist who used the Rosetta Stone, found in 1799 by a French army engineer, to translate and interpret ancient Egyptian hieroglyphics. Only in Roth's case, his cipher is a motion-capture application of his own invention.

To create the piece, Roth deployed his motion-capture computer application, which works on a series of photographs, to 'make visible a graffiti writer's unseen movements when creating a tag', according to the exhibition's curator, Thomas Delamarre. The writers' motions are visualised in symbolic form and projected on the surfaces of buildings, offering a digital representation of how a tag is created. Roth's form of virtual graffiti is expensive and time-consuming to create, which is precisely why it fits the foundation's concept of its mission.

'The foundation evolved out of a conversation between Alain Dominique Perrin and Cesar [a prominent nouveau-realist French sculptor who died in 1998],' says Ilana Shamoon, one of the foundation's curators. 'Mr Perrin asked Cesar what artists needed and he said, 'They need money and they need space' and that has been the basis of the foundation ever since. Our goal is to give artists the tools they need to create and a venue to show their work.'

Of course, nothing in art or commerce is ever that simple. The relationship between the two has become more suspect because of the way some brands involve artists in the creation of products, the most notable example being Louis Vuitton. Artists such as Takashi Murakami and Richard Prince have been drafted into Louis Vuitton's showrooms as salesmen through their work with leather goods.

'There are different ways for luxury brands to interact with artists,' says Shamoon. 'I think LVMH [the holding company under which Louis Vuitton operates] has a very specific way of interacting; there is a direct relationship between its products and artists and all the artists that it works with create lines that are sold in its stores, which is not the case with Cartier, where we always try to separate those two things.'

In May, Louis Vuitton took over the Hong Kong Museum of Art for the exhibition 'Louis Vuitton: A Passion for Creation', wrapping the building in work by Prince. The exhibition included young Hong Kong artists but some in the city's artistic community displayed open hostility towards the project.

Professor Helen Grace, deputy head of cultural and religious studies at the Chinese University of Hong Kong, condemned the exhibition as 'an appropriation of 'general intellect' within an explicit branding exercise' that had turned the museum into 'the latest LV shop' and a 'mouthpiece' for the luxury brand. Grace acknowledged in a critique she wrote for the monthly journal CforCulture that the Louis Vuitton art foundation is a 'very good one' but she also condemned the exhibition as 'the appropriation of creativity and the subordination of it to a brand name' and she likened Louis Vuitton's occupation of the museum to an 'instance of extraterritoriality' similar to the French appropriation of its Shanghai concession during the colonial era of the 19th century.

When Bernard Arnault, chief executive of LVMH, is asked about Louis Vuitton's 'artistic and creative imperialism', as some have called it, he tends to shrug his shoulders and point out that nobody at Louis Vuitton has put a gun to the head of any artists involved in the brand's many creative projects. Many have been very happy to take Arnault's euros and, in any event, Louis Vuitton is not alone in its forays into art. Every luxury brand that wants to be taken seriously now seems to seek an association with leading artists and the creation or acquisition of iconic buildings to house their foundations.

Francois Pinault, founder of the PPR group, which controls Gucci, was listed in 2005 and 2007 as the most influential person in the art world by ArtReview magazine and he recently installed his enormous collection of contemporary art in Venice's Palazzo Grassi. Closer to home, the Diesel store in Central is currently housing work by eight contemporary artists, who were given custom-made hawker stands and asked to use them as a framework for installations. One, by the New York-based Japanese artist Lady Aiko, features a high-concept version of graffiti art.

'I was happy to be chosen by Diesel,' says Aiko. 'Without its backing I would not have been able to find the time and space to do the work my heart wanted me to do.'

But the essence of Grace's argument, which has many supporters, is that the flood of luxury-brand cash into the art world has curtailed creativity and freedom of expression. Artists have been subverted to the commercial process, becoming prostituted participants in a sleight of hand that persuades consumers to pay enormous prices for utilitarian items such as bags, belts and wallets because the imprimatur of artists on these items carries a subliminal message of good taste.

The process also gives the brand a new way of selling the same thing. Where once Louis Vuitton had bags in dark brown and beige with the classic LV logo, it now has a multitude of the same bag with colours and additional motifs designed by flamboyant artists such as Murakami and Prince, all of which tend to have higher prices than unadorned merchandise.

This is precisely the kind of crossover between art and commerce that Cartier has sought to avoid.

'Contrary to what everybody thought, I wasn't trying to create a new way to sell watches or jewellery to the elite,' says Perrin of his decision to set up the foundation. 'In fact, I expressly forbid any link between Cartier products or advertising and the foundation. The only reference to the brand is the logo in the foundation's name.'

Of course, that's a very big 'only', for it means that everything the foundation produces has the very recognisable Cartier logo front and centre. Nevertheless, foundation staff are vigorous in their assertions of independence; even when the foundation sponsors work by cross-cultural artists who are regarded as criminals.

'There is an irony in that,' says Shamoon. 'People do have a stuffy impression of Cartier. But the amazing thing is that there really is a fecund freedom for the foundation to do whatever it wants to do.'

That has led to a series of groundbreaking exhibitions, some of which have pushed the boundaries of good taste, including one that featured explicitly sexual photographs by film director David Lynch and couture fashions created by Jean Paul Gaultier that used bread rather than silk or muslin as a raw material. And next year, the foundation will play host to a series of paintings by the anarchic Japanese filmmaker and comedian Takeshi Kitano. For these exhibitions, and the current show, no gift shop has been created to feature Cartier watches decorated with Lynch's photos, Gaultier's sketches or the hieroglyphics of urban graffiti.

So, if Cartier plans to keep to its pledge that the brand and the foundation's artists will forever be separated, what does Cartier get from its association with the arts, especially at a time of economic uncertainty when profit margins are being squeezed?

'I think it's being able to show potential clients and even the general public the nature of Cartier's dedication to contemporary art,' says Shamoon. 'And also their dedication to the general public, which is something they are not able to achieve with their jewellery because it's obviously not accessible to the average person.'

So that's it? Cartier spends all this money on art and artists just to promote creativity and hand something to the nine-tenths of the population who cannot afford a million-dollar necklace? Shamoon insists that this, and nothing else, is the Cartier Foundation's mission.

'It's important for us to reach as many people as possible,' she says. 'We are here as a kind of service for the general public, to assist them to discover contemporary art.'

On the floors below Shamoon's office, the gen- eral public is present in their hundreds. 'Born in the Streets' has been a great success, with more than 80,000 visitors so far, a number that led the foundation to announce last week that it had extended the exhibition by six weeks past the original closing date of November 29.

In the basement gallery a tour is being led by Delamarre. He pauses in front of some work by P.H.A.S.E 2 and embarks on a rhapsodic description of the 'bubble' and 'wild-style' forms of graffiti lettering that the New York artist developed and made his own. A family of three - mother, father and son - join the edge of the tour and listen. The curator becomes serious as he laments the campaign launched by the New York Police Department to 'buff' (eradicate) the city's graffiti. The mother of the family has heard enough intellectual exposition.

'I gotta tell you, pal, in my neighbourhood [which from the sound of her accent is probably Brooklyn] we were damn glad when the cops showed up,' she says with a snarl, as the curator recoils at the sound of art and reality colliding. 'It was no picnic having all that graffiti around and it always meant more crime.'

The curator shrugs off the encounter. He has no time for such apostasy. He needs to move on to the film section. Meanwhile, colleagues of his are preparing the Cartier Foundation's children's programme, which includes, on October 27 and 28 and November 2, a graffiti workshop for children aged 12 and over, followed by a session on November 7 called 'Hi my name is', in which those who are eight and over can discover 'the universe of graffiti' and 'choose a pseudonym' for later use in the streets and subways of Paris.

These programmes, and the choice of graffiti as a subject matter, suggest Cartier is serious about keeping art and commerce apart, despite the very obvious success of brands such as Louis Vuitton in bringing them together. But what if that success one day makes Cartier's number crunchers jealous? What if they decide to create a Cartier tank watch with the case decorated with Roth's graffiti archetypes?

'That would make me feel queasy,' says Shamoon. 'I think that kind of mix would go against the goals that Cartier has been trying to achieve with the foundation. So in that sense it would be disappointing.'

Not that Shamoon has much to fear. Later in the day, a Cartier staff dinner takes place in Les Ombres, a restaurant above the Musee du quai Branly. The idea of a Cartier tank with graffiti decorations is discussed and rejected. And compliments are given for the clever way in which the foundation has allowed all of the graffiti artists in Paris to come to the exhibition and write on a billboard outside.

'But what,' somebody wonders, 'would Cartier feel if a graffiti artist from the exhibition went 'off-campus' and decided they didn't want to write where they were told to but, instead, for example, decided to spray graffiti all over the windows of the store in the Place Vendome [a neighbourhood where activities such as graffiti art are vigorously and effectively discouraged by police officers and security guards]?'

Katharina Baigneres, director of international press and events co-ordination for Cartier, thinks the question over, but not for long.

'I would rather have an artist spray graffiti on the windows of the Place Vendome store than have Cartier make a watch with graffiti symbols,' she says, with some emphasis. 'The first would be art, the second would be a kind of desecration.'

AND THAT BRINGS us back to Evan Roth. He's still not happy about writing on the Cartier store window, it still feels too much like helping 'the brand' as opposed to promoting his art. Then he has an idea.

'I could have another graffiti artist doing the writing and I'll stand in front with a T-shirt on that has the slogan saying 'I am not happy with this photograph'. That would work.'

For him maybe, but not for us. Instead we cajole him into the studio with a fashion photographer and stick in his hands two spray cans, which he doesn't normally use, being more of a felt-tip man. Roth's not happy about the cans but then, whatever Cartier may say, happiness and artists, like art and commerce, have never been easy bedfellows.