Judges Dredd (Karl Urban) and Anderson (Olivia Thirlby) serve as judge, jury and executioner in Director Pete Travis’s movie adaptation of the popular comic book series, “Judge Dredd.”

“There are certain points in your career,” Karl Urban says somewhat incredulously, “where you can’t believe they’re actually letting you do what you’re doing.” Urban, as the law-dealing Judge Dredd in “Dredd 3D,” got to race through the streets of Cape Town, South Africa, on Dredd’s “Lawmaster” motorbike. “I wouldn’t let anyone else have the fun!”

Manifestations of such levity, however, were few and far between in the finished product. The film, which is based on the eponymous British comic strip, follows Judges Dredd and Anderson (Olivia Thirlby) as they attempt to take down a drug cartel operated by the ruthless Ma-Ma (Lena Headey) in a futuristic American police state. Beside some self-aware humor, the film is by and large a dark one. Dredd attacks, sentences, and kills criminals in a dank, overcrowded apartment complex rife with poverty and violence. Though the film is set in the dystopian Bos-Wash corridor known as Mega City One, its singular focus on the drug trade in one (albeit massive) apartment building, Peach Trees,  is remarkably claustrophobic.

For Urban, however, the setting wasn’t the only thing that was claustrophobic. Part of Dredd’s iconic costume included a helmet that obscured all of his face, except for his mouth, for the entirety of the film. “It took a while to figure [the helmet] out,” he said. “It was a challenge, and not only because my eyes were invisible but because of the fact that the character of Dredd operates within a very narrow band. He is a man who has been trained to keep his emotions in check.”

How then could he convey the character’s feelings? “The tools I had available were voice and physicality—those became extremely important in how you do something.”In order to research Dredd’s character, Urban, who was an avid fan of the comics when he was younger, welcomed the chance to indulge in nostalgia. “I got the voice from a particular panel I found in one of the comics which described Dredd’s voice as being like a saw cutting through bone, and that just resonated with me,” he said. “In our movie, Dredd uses his voice as a weapon, so I needed something that bridged that spectrum.” Urban was dedicated to organically creating Dredd’s voice without computerized enhancement, and in the end, the gravelly, powerful voice in the movie is his alone.

Though he was committed to embodying Dredd as fully physically as he did vocally, Urban ran into roadblocks early on. While filming “Red” in 2010, he had displaced his neck on a bad landing; he thus spent much of the three months he was allotted to get into shape for “Dredd” in and out of physical therapy. “It was daunting because of the way that the character was drawn,” Urban said. “He’s got this incredible physique, and there was a real pressure to get there.” He managed it in the end, but it wasn’t fun. “It was three months,” he said ruefully, “without booze and beer.”

In seeking to embody Dredd’s character, however, Urban explored far more than his voice and physical presence. “I discovered this whole plethora of stories that had been written subsequent to my reading the comic,” he recalled. “There was an incredible evolution in the maturity of the writing and this wonderful depth to the character that wasn’t really prevalent in the comic when I was reading it. You really get to understand the internal conflict within the character of Dredd.”

One main challenge of his role would be to externalize the feelings of such a stoic, ruthless character. “He has been trained to keep his emotions in check,” Urban said. “Consequently it was very important for me to identify how to humanize the character as much as possible.” In the end, it boiled down to one main goal: “Where is this character compassionate?”

Without his face to convey emotion, Urban brought out his character’s conflict through a heavy reliance on movement. Though Dredd starts off the film quite tightly-wound, as Urban put it, his ability to contain his physical reactions starts to crack as he witnesses a barrage of corrupt dealings and deaths in Peach Trees. “There’s a loss of innocent life in the film,” Urban says. “You see a significant gear shift in Dredd.”

“In the beginning of this movie you have this character who sees the world in terms of very black and white, right and wrong,” he explained. And it is this character’s evolution that forms much of the film’s emotional crux, 3D and startling graphics aside. “At the end of the film he’s just suddenly discovered this whole gray area, and that represents this fracture, this paradigm shift. Once you see something in life you can’t un-see it.”

—Staff writer Leanna B. Ehrlich can be reached at lehrlich@college.harvard.edu.