Justice being seen.

Exploring themes of openness and transparency allied to tectonic expressiveness, Bordeaux's new law courts are a dramatic synthesis of construction and function.

Since the early 1980s, French cities including Lille, Lyons and Montpellier have been busy reinventing themselves as dynamic regional capitals. Bordeaux, a dense, mercantile city with broad quays onto the Garonne and architectural set-pieces from the Enlightenment, seems intent on pursuing similar commercial and institutional ambitions. Now with a new mayor, former premier Alain Juppe, Bordeaux is aiming to be a location for innovative, even spectacular architecture and planning (by Fuksas, Foster, and Perrault, among others) and so become the clear urban focus of France's south-west.

As part of a nationwide programme for the construction of new court facilities - courthouses in Grasse and Lyons by de Portzamparc and Yves Lion plus upcoming projects in Nantes and Pontoise by Nouvel and Ciriani respectively - the Richard Rogers Partnership (RRP) has satisfied both municipal and judicial desires with its recent additions to the Bordeaux Law Courts.

The RRP solution is both an interesting re-ordering of a complex inner-city site and a provocative mechanism for the contemporary implementation of justice. To the weight and opacity of the old city, it adds lightness and transparency.

The immediate context is well described as a cite judiciaire as the architects' approach is to interconnect several existing buildings to confidently occupy an entire city block. They inherited fragments of the medieval Fort du Ha including two robust towers, an awe-inspiring Classicist courthouse from the early nineteenth century, and a curving School of Magistrature (French judges have own their educational system). The RRP scheme completes the block's western flank, creates a circulation route from the nineteenth-century hallway and bridges across to the 1970s school to house a restaurant. It then nudges up against the ancient fortifications with a mysterious pool designed, but not yet realized, with artist Anish Kapoor.

The long, western block of this judicial compound is the grandly named Tribunal de Grande Instance. Offices for judges and administrative staff are stacked in a five-storey linear block over four storeys of parking garage (more than 300 people work in the building). A delicate copper roof floats above this block to extend eastwards out over seven vat-like forms aligned and clearly visible behind a taut curtain of glass. These are the courtrooms isolated in the animated concourse and washed in zenithal light as they pierce the building's canopy. Held on stubby concrete props, the vessels are wrapped in cedar above saucer-like concrete floors. They are then connected with delicate walkways and bridges and steps so that the privacy of legal procedures inside is maintained but that the toing and froing of plaintiffs and lawyers, judges and the merely curious is on theatrical display.

Few of the cases held in the new Rogers building are of a highly sensitive or criminal nature. Although there is provision for the protected basement access of witnesses and accused, the architects' strategy is to make the routine and ceremony of the legal process as transparent and unintimidating as possible. The formal public entrance from the street is upwards by a cascading metal stairs, past the awaited Kapoor pool (which will also aid the building's cooling system), and onto a terrace, with views back to the St Andre cathedral, beneath the first of the cedar-clad chambers. This initial courtroom, intended specifically for juvenile cases, is exposed to the exterior but nevertheless sheltered by the communal canopy. Unfortunately, it is easy to mistake the secondary entrance below, next to the office slab, as the main entrance.

The visitor then pierces the glass wall to discover the undercrofts of the other six chambers in a complex and almost kaleidoscopic perspective of articulated struts and soffits. This is the so-called Salle des Pas Perdus, a luminous 14m high loggia. With a simple security desk separating visitors from employees and officials, each courtroom has its own stairway (like the boarding apparatus for a plane or ship) to the glass-floored catwalk which connects all the chambers one floor above. The vast western wall, over 80m long, is held by structural glass fins, some of which have shattered since the building was completed a year or so ago. This fault was caused by aluminium washers of an unspecified grade being used. Since their modification, there has been no further failure of the glass fins, but the client has instructed that they be replaced with lightweight steel trusses.

If the paths of the participants in legal dramas are fully exposed, the actual courtrooms are remarkably introverted. Cocooned within the barrel-like forms, the courtrooms are accessed through hinged doors which, when closed, lie flush with the curved shell of the timber pod but, when open, proceed forward and slide to either side as in aircraft entrances. Inside, the rooms are exaggeratedly vertical, soaring upwards through oval rooflights to the blue Gascon skies. This is a peculiar form, but each pod is exquisitely made; more peculiarly still, some are subdivided into two small chambers separated by full-height mirror. The sides of each courtroom, curving and slanting inwards, are made of flush pale plywood panels. Heat, sound, acoustic absorption, emergency and electrical services are all neatly housed behind these units with the various small openings making for interesting geometric decoration. This ornamental character to Rogers' work - a blatantly visual pleasure in design - is evident both in the sleekness of the courtroom silos and the plethora of structural elements which hold the umbrella roof in place. The rotund shape of the courtrooms may recall the traditional wine vats of the Bordeaux region, and their repetition the sheltered chambers of Le Corbusier's High Court at Chandigarh, but this acute streamlining also allows for the rapid expulsion of warm air (the building's ventilation is almost entirely natural). The primary structure of the tribunal building is of tapering steel columns, with tie rods within the vault and three-dimensional braces consolidating the middle zone. The complex and skeletal structure of the foyer reveals Rogers' Gothic instincts and an affinity, perhaps, with the expressive constructions of Viollet-le-Duc over a century ago.

As the vaults are unidirectional, the long street and court facades are topped by a seven-part scalloped fringe. It is the shorter, north facade which alone depicts the true building parti: there the vault reads as a straight visor underneath which the office block and the raised courtrooms flank that intermediate chasm which the uninitiated may mistake as an entryway. To call this inner space between the principal offices and the courtroom loggia an internal street is misleading - it is two floors beneath the loggia and comparatively empty of life. Three storeys of offices are skinned in glass to stop short of the roof leaving space for a penthouse floor glazed almost seamlessly into the vault soffit; the west facade is screened in moveable blue steel panels for afternoon sun protection. In a traditional gesture, RRP has wrapped the base of the project in a stone band which becomes the plinth (housing more offices) on which the courtrooms stand.

Is this a formal or an informal architecture? So many of Richard Rogers' buildings look like oil rigs, albeit splendidly tailored ones, that one wonders whether exposing all, or almost all, to public view is a functional consideration or a metaphorical one. As politicians now equate physical transparency with democracy, RRP believes that revealing the bones and ligaments of a building make it more appropriate or acceptable to a modern open society. In Bordeaux, the organs of the building, the courtrooms themselves, are understandably screened from view but risk, perhaps, becoming even more secretive, more intimidating. In 150 years, will this supposed informality not, in fact, make for a very fixed hierarchy and pattern of use? In the shorter term, the citizens of Bordeaux certainly have something to talk about.