Grice was a distinguished and charismatic street judge in Mega-City One, holding the rank of Senior Judge. During Necropolis in 2112, he had been one of the judges brainwashed into serving the Dark Judges .
In a meeting of senior judges after the crisis, he and his colleagues were left unimpressed with the mental state of the returning Chief Judge McGruder and he gently mocked her in front of everyone. He went on to advocate a tightening of judicial control in the face of public outrage at the Justice Department's failures during Necropolis. However, Judge Dredd persuaded McGruder to permit the citizens to vote (in 2113) in a referendum about whether the Judges should continue to rule the city, or whether democratic government should be restored. Grice was left outraged and argued against it: when he pointed out Dredd was "outvoted", Dredd snapped back "you don't believe in voting, Grice" and forced his view on the rest of the judges.
This controversial scheme was unpopular with many judges, and Grice assumed that the result was a foregone conclusion: that the people would vote to remove the Judges from power. Firmly believing that this would result in total chaos, Grice formed a conspiracy with half a dozen other judges to prevent the referendum from happening. They planned to assassinate Dredd, reasoning that since Dredd was almost the only judge who believed that the Judges could win the vote, then without him all support for the referendum would disappear and McGruder would cancel the project.
Dredd survived the attempts on his life, personally killing two of the conspirators and quickly rounding up the others. In a rare lapse of regard for the law, Dredd actually assaulted Grice after taking him into his custody, since he believed that the people would vote to keep the Judges in office because of their reputation for integrity, but that once the people heard about Grice's crime that myth would be dispelled and the Judges would consequently lose the vote. Grice attempted to defend himself but was defeated, a humiliation he would never forget. He was summarily sentenced to twenty years of hard labour on the penal colony on Titan. His captivity on Titan was recounted in his own series, Purgatory.
Conditions on Titan were extremely harsh, and prisoners were frequently tortured and brutalized by the guards. Grice became bitter and violent, and exercised frequently to increase his strength; he also gained a reputation among the other convicts.
After enduring two years of his sentence, Grice escaped from his cell and led a mass breakout, killing the governor and many guards, and stealing a dozen or so spaceships. He also stole a biological weapon, the "Meat Virus," which had been discovered on Titan and which was being examined by biological weapon scientists. Hundreds of violent prisoners escaped with him. Purgatory ended at this point, but the storyline was immediately taken up where it left off in Judge Dredd: "Inferno" by Grant Morrison and Carlos Ezquerra.
Grice attacked Mega-City One, first by crashing his stolen ships into major buildings and then by unleashing the deadly Meat Virus on the population. Normally his rebels would have been quickly exterminated by the Judges, but they were weakened by the symptoms of the virus, and were forced to retreat to the Cursed Earth outside the city while the rebels wreaked havoc and killed indiscriminately. Chief Judge McGruder was captured and tortured almost to death, and Dredd himself nearly perished in an unsuccessful rescue attempt.
Grice assumed the office of chief judge, and began passing insane laws which he capriciously changed from day to day. Even one of his own followers began to question his sanity, and eventually turned on him. Anticipating this, Grice had the traitor killed, but even his loyal comrades were not safe from Grice's wrath: he also publicly executed one of his most dedicated men with a chainsaw, one of the judges from his original conspiracy to prevent the referendum two years earlier.
However, Grice's men were heavily outnumbered by the Judges, and once the Judges had regrouped from their initial setbacks Dredd led them back on the offensive. Storming the city, they made quick work of the escaped prisoners. Grice had a mental breakdown and began destroying the interior of the Grand Hall of Justice with a flamethrower and shooting his own men. Dredd confronted him personally. Even on this second occasion Grice almost got the better of him, but Dredd repeatedly ran him over with his Lawmaster Bike, until he was totally crushed.
He's shown at first to truly believe that the Judges are the best thing for Mega-City One and opposed the referendum due to him believing that the citizens would vote to disband the Judges but he started to become more of a extremist when he along with dozens of his fellow Judges started a conspiracy to assassinate Judge Dredd, but it failed and he was sent to Titan.
The conditions on Titan has made Grice a man full of hatred and anger and after starting a mass breakout he slaughtered the guards and the governor, he then launched an invasion of the Big Meg and had a callous disregard for the civilians he's supposed to be protecting, such as crashing ships into buildings and unleashing the deadly Meat Virus which numerous people. He also treats his men horribly, such as coldly executing one of the most dedicated men who was part of the conspiracy to assassinate Dredd.
At the end he went completely went insane and psychotic and started destroying the Grand Hall of Justive and slaughtering his own men.