"No one wants to die," writes Mutope Duguma, imprisoned in Pelican Bay State Prison, Northern California. "Yet under this current system of what amounts to intense torture, what choice do we have? If one is to die, it will be on our own terms." Mutope was among thousands of prisoners on hunger strike across the state to protest conditions in California prisons. Prisoners at Pelican Bay ended their hunger strike last week, after prison officials agreed to review their policies. The strike continues in other prisons.

Nearly 12,000 prisoners began the hunger strike two weeks ago, according to prison officials. Among them were prisoners from California incarcerated out of state in Arizona, Mississippi and Oklahoma who joined the strike in a powerful act of solidarity. According to Todd Ashker, a hunger strike representative in Pelican Bay Security Housing Unit, or SHU, an important aspect of the protests has been that prisoners have united across racial lines. "When people come together and recognise who the real enemy is, who is really the cause of all their problems, they have a lot of power," he says. Prisoners have five core demands, key among which are the abolition of long-term solitary confinement and the reform of the controversial policy of confining prisoners deemed to be gang members.

Protests started with a three-week hunger strike in July at Pelican Bay SHU, where more than 1,000 people are currently detained. They have called themselves "the buried class". The controversial units are used to "lock down" people in long-term solitary confinement, for years and sometimes decades. California is now holding more inmates in solitary confinement than ever before; approximately 3,238 people are detained in these units across the state. Inside SHU, prisoners are caged for at least 22 hours a day in 8x10ft, windowless cells and have no human contact except when guards put shackles on them. In 1995, a US court held that conditions in SHU "may press the outer bounds of what humans may psychologically tolerate". "There's a notion with many people that the worst of the worst are put in Pelican Bay," says Manuel La Fontaine, an organiser with All of Us or None, "but I've got news for people: the worst of the worst is Pelican Bay."

Isolation is state-sanctioned torture. Harvard psychiatrist Stuart Grassian, an expert on the effects of solitary confinement has said, "in some ways, it feels to me ludicrous that we have these debates about capital punishment when what happens in Pelican Bay is a form of punishment that's far more egregious." Pelican Bay is hundreds of miles from home for most people inside the prison, further isolating them from their families, friends and communities. Among the demands of the hunger strike is to be allowed to make a phone call home and send a photo of themselves to their loved ones once a year. That the authorities deny them these rights is indicative of a system that damages not just the person inside prison, but their communities as well.

One of the main reasons prisoners get sent to the units is because prison officials label them as members of a "gang"; this is part of a wider strategy to dehumanise and criminalise members of our communities. The only way to be released from SHU is if a prisoner agrees to give information, or "debrief", about other prisoners or people outside prison, including their own family. Many prisoners are "validated" as gang members with evidence that is clearly false, or fabricated by other prisoners in order to leave SHU themselves. As a SHU prisoner writes, "The only way out is to debrief, die or parole. They want to break us. If this is not torture, I don't know what is." According to figures released by prison officials in August this year, some 500 prisoners in Pelican Bay had spent more than 10 years in SHU confinement and 78 more than 20 years.

Despite the worsening medical condition of the hunger strikers, Governor Jerry Brown and the California Department of Corrections and Rehabilitation are refusing to meet their demands. Instead, they have responded with repression against prisoners, their families and supporters, and are treating the protest as an "organised disturbance". Prisoners in the general population who support the strike have been transferred to solitary confinement and family visits have been cancelled.

"We have to resist it now – we can't wait," says Todd Ashker, "because we've been enabling them to keep doing this for 20 years. If we weren't participating complacently, they can't do it." Outside prison, we cannot be complacent either. As Deirdre Wilson of the California Coalition for Women Prisoners says, this is an international issue "because whatever the United States does domestically has an impact on what is allowed to happen internationally". When people inside prison speak out, we need to make sure their demands are heard.

Hundreds of hunger strikers are continuing to risk their lives to abolish an oppressive system, refusing to eat until their demands are met. Despite retaliation they are determined to continue. "I myself plan on taking this to its bitter end," writes another SHU prisoner. "We know their policy of forced feeding. The mechanical restraints, the nasal gastric feeding tube shoved up the nose, being put in a holding cell to ensure digestion, the brutality of this policy, the knowing that it will be done repeatedly." His letter ends, "We know this is it. We know we make change here and now or never."