For the first time in my life, I could imagine actually looking forward to jury duty. Unlike those ponderous fortresses that typically shroud one’s civic obligation in gloom and doom, architect Rafael Viñoly’s Bronx County Hall of Justice, which opened its doors last month, epitomizes the notion of “innocent until proven guilty” — and doesn’t condemn the rest of us who must pass judgment. It is, perhaps, the least Kafkaesque courthouse in the city — a welcoming, translucent nine-story structure on 161st Street with a long, elegant façade of corrugated, green-tinted glass resembling Astor Piazzolla’s bandonéon.

Its project director, Fred Wilmers, called the courthouse “a metaphor for the transparency of the judicial system, the openness of government.” It is an apt description of this structure, with its street-level entrance and its exhilarating, light-filled lobby that’s not the least bit oppressive.

It’s an architectural (and a metaphorical) antidote to the concrete, bunker-style Bronx Family/Criminal Courthouse across the street, and it’s less intimidating than the Bronx County Courthouse a few blocks west, near Yankee Stadium. The new $421 million building, impressive but not imposing, takes on some of the criminal functions of its overextended neighbors.

You still have to pass through metal detectors and X-ray machines before gaining entry, but Mr. Viñoly’s idea of respect for the public above authority is delightfully successful. The centerpiece of the L-shaped configuration is the jury assembly room, a rotunda-like space that could hold 570 people in the center of the lobby. Skylights allow daylight to flood the space, which symbolically puts the juror at the center of the judicial process with dignity. What an idea.

After you are assigned a case, you can take an elevator to one of the four court-dedicated floors. Or you can stroll up the ramp that spirals around the rotunda to the second floor, offering a continuous view of the tree- and bench-dotted courtyard outside. It’s the designer’s stated hope that once this public plaza is opened later this year, the staff and local residents take their lunch breaks out there; a greenmarket has even been invited to camp out in this neighborhood-integrating social space, graced by a site-specific granite sculpture of interlocking cubes by Cai Guo-Qiang, who currently has a show at the Guggenheim.

On the second floor and above, broader views of the neighborhood open up: homes, a church-run grade school, and a public high school. You can even make out part of the Viñoly-designed Bronx County Housing Court, constructed of brick and glass cubes, which went up in 1997 on the Grand Concourse.

In the new courthouse, glass rules — making surveillance of all public spaces within the building child’s play for the overabundant court officers. Natural light filters into the white-walled, wood-paneled courtrooms, some of which are outfitted with state-of-the-art video technology. Jury deliberation and attorney-client rooms come with each, while waiting rooms for jurors punctuate the ends of hallways. There’s a separate circulation system for the staff and judges along the building’s luminous perimeter — that’s why the façade’s glass is fritted, allowing some privacy from the outside.

While no one should throw stones, let alone explosives, at glass courthouses, the Hall of Justice’s translucent skin is assuredly blast-resistant. It has less to do with the September 11, 2001, terrorist attacks than with the bombings of the Oklahoma City federal building in 1995, and of the embassies in Kenya and Tanzania three years later; after all, the new Bronx courthouse was first conceived of nearly 17 years ago. The Giuliani administration challenged the security of Mr. Viñoly’s vitreous design, so after a “vulnerability analysis,” the architect upgraded the curtain wall with laminated glass that doesn’t shatter and stays in its sturdy frames. The judges’ chambers on the top two floors have bulletproof panels inserted into the glass.

“The challenge was obvious: to demonstrate that the building can be transparent and, at the same time, secure as any other,” Mr. Viñoly told The New York Sun during a recent telephone interview. As open and friendly as this building is, it’s still no picnic for defendants. In from Rikers Island for their trials, the detainees are put in holding cells with bars and concrete walls until sequestered into the courts through a hidden circulation route. But one of the court officers let on that he thinks courthouses should be ominous and forbidding — an old-school reaction that demonstrates just how successful Mr. Viñoly’s achievement is.