When the Paris office of US firm Gibson Dunn & Crutcher threw a party, it did it in style. Abigail Hansen discovers why managing partner Bernard Grinspan came up with such a bizarre idea.

The classic building on rue du Faubourg St Honoré is lit by massive floodlights. Eerie mist trails from the lobby, a metal-caged lift descends, while a semi-naked acrobat dangles high above. Inanimate dummies are propped throughout… or are they people? Violent graffiti covers marble walls and neon dragon signs flicker above doorways.

A Chinese stall here, an Indian orchestra there, a Moroccan tearoom around the corner. A fortune-teller reads palms, a magician does card tricks, belly dancers twirl with abandon, massive pythons are draped on their young fragile mistress.

Further up the building, there are countless video games which black-tied men play earnestly while silk-clad beauties giggle in delight. Begoggled bartenders, suspended horizontally from chains, serve drinks with aplomb, techno music throbs, while a massive ice sculpture slowly melts.

Onward and upwards, where grass sprouts from the floors, an entire room blossoms with flowers and birdcages, and another clatters with whimsical gadgets. Monitors relay images from other rooms, or mutely display insects, fish, deserts. Bizarre characters float around in fluorescent wigs, futuristic dresses, flashing shirts.

There are indescribably dense layers of activity, odour and sound. It is as if you are somewhere else, in another universe, isolated from the rest of the world. A velvet voice resonates and there comes a ghostly airport announcement: "Welcome to Gibson Dunn & Crutcher."

Welcome, indeed, to the Paris office of the 700-lawyer US firm, where managing partner Bernard Grinspan decided to throw a party which he admits he wanted to take to the extreme. Even so, he feels that he did not go far enough.

Of event designer Béatrice Mirrione, he says: "I was pushing her to be even more creative, but I had technical limitations. I wanted an entire room filled with screens, a whole visual environment, but it was several tons of equipment."

Grinspan agrees that the allure of the evening was the multitude of cohesive entertainments and environments. He says: "The concept was to have a science fiction environment, where there was a lost paradise on one floor, further down something more technology-oriented, and at the bottom – the street level – a Blade Runner kind of thing. In the end, the difference is in the detail. The danger we had was vis-à-vis the clients, that we would try to do something different but do it in a clumsy way. It's one thing to convey creativity but you also have to convey professionalism."

Mirrione, a former teacher who has her own company, says she observes the personality of the client, creates the concept, then subcontracts specialist companies. Everything is always made to measure and unique. She admits that this was the first time she had designed an event for a legal practice but says the biggest challenge was the extremely short timescale.

She started with the personality of the Paris office of Gibson Dunn. "I immediately perceived an obvious style, a certain image of the firm," says Mirrione. "It was clearly necessary to do something different, at the highest level."

Mirrione says Gibson Dunn's technology and its choice of furnishings correspond to an environment which is quite different from the usual firm. "Bernard is very technologically minded and I thought of films such as The Matrix," she explains. "I did research on similar films, searching for recurring images. What kept coming back was the street, then the technological level, and then the level of luxury. The layout of the premises gave a density that would have been missing in a single, large room. Everyone had the impression that they hadn't seen everything. They got lost. All this came from Bernard's personality."

The logistical, practical and time considerations for the party were extraordinary. Planning started six months in advance, and from the concept itself to the selection of artists, music, caterers, food, décor, lights, costumes, and cigars, everything was made to measure.

In addition, the firm had to inform the police, the fire brigade, and of course neighbours, who were put up in a hotel for the night. Gibson Dunn needed to obtain parking permission, hire electrical generators, air-conditioning, furniture removers, taxi and valet services, and organise the security of client files. Lawyers were sent home with laptops two days before the party to minimise disruption to clients, and were back in the office the afternoon after the event.

Grinspan says the main target of this event was the firm's existing clients and people it had worked with over the past 10 years. He also aimed to attract general interest in the firm, to increase staff morale and to mark the Paris office's presence within Gibson Dunn as a whole.

The least important aspect for him was marketing Gibson Dunn to people who did not know the firm, and while such an event creates a buzz, he insists that this was incidental. Valérie Roussilhes, Paris marketing director of Gibson Dunn, says: "The aim of the soirée was first to thank the clients and to show the international activity of Gibson Dunn. It was also a way to present ourselves to potential clients, to show them our originality and to position ourselves in the top commercial law sector. We wanted to avoid something déjà vu or in bad taste. We work in a very conservative world, but I think a lawyer can be creative, and we wanted to show that."

Grinspan agrees. "We tried to be as different as we could, and I think that is truly what we do every day."

Roussilhes adds: "In this competitive profession, you need to differentiate and position yourself, and create an image. But most firms completely confuse marketing and communication. Why? Because lawyers look for return on investment, whereas marketing has only a long-term impact. I decided that in order to have an identity which was coherent with the soirée, we were going to be different, original, innovative.

"In France you don't yet have the concept of marketing that you have in the US, primarily because of the profession's rules regarding communication and advertising. The Ordre is afraid that the image of the profession in France will be lowered. But these very restrictions can force you to be creative in a different way. In the US they do advertising, they compare, they train lawyers about selling methods. In France you find that nowhere. If you speak about the profession as a product that we sell to the clients, with a price and a distribution network, they don't understand. If you try to do a satisfaction study, to find what clients think, partners will say it's not worth it."

Grinspan, on the other hand, does not think that he had any limitations imposed by the general legal culture. "There are certain things that I would not have put [in the party], but there was no sense of limitation, at least not in terms of what is proper vis-à-vis the legal community," he says.

Having worked for a number of years in the US, he says that in France they are also conservative but in a different way. "If you had to weigh one against the other, you would probably say that the French legal community is slightly less conservative as a whole than the US."

Catherine Potton-Lefevre, marketing director with Gide Loyrette Nouel – which claims to be the only French firm with a separate marketing department and which considers itself to be a pioneer in the field – thinks the French market is becoming less conservative. She says the market is becoming more international and competitive, and professional rules are being relaxed, allowing firms to develop the still-new marketing aspect of their practices. So marketing, in her view, is developing an increasingly recognised function within firms.

Grinspan has received unanimously positive feedback about the party and feels that, rather than being ephemeral, the event will have a long-term resonance.

"It was essentially like a play or a movie for one night," he says. "I don't think the firm, in a hundred years, has ever done anything like this. I don't know when we'll do another one, but we won't do another one like that anyway. I already have some ideas!"

Roussilhes thinks such an event can be considered an investment. She says: "The return is perhaps not financial, but will be in terms of image. To measure that is difficult."

Mirrione is clear, however, about the image she has of Gibson Dunn. "It is a firm which dares to risk. A firm that is going forward and which says, 'Look at us, we do things that are different and we do them well.'"