I learned about a law this week governing the use of solitary confinement, one that I had never heard of before. To be precise, this isn’t really a law – more like a very strongly worded guideline, albeit one published by an important federal agency. It says that an individual should never be locked in solitary confinement, except as an absolute last resort. It mandates that individuals, when in isolated confinement, must have the ability to socialize, to communicate, and to physically interact with other individuals.

This would be great news for those of us working on solitary reform, except for one thing: this guideline doesn’t apply to humans; it applies to mice.

According to the National Research Council’s basic standards against cruelty in the treatment of laboratory animals, all this and more is necessary to prevent negative physical and mental health deterioration, which are well-documented consequences of long-term solitary confinement.

I learned about these guidelines from Dr. Brie Williams, at a national gathering on solitary confinement reform. When Dr. Williams discussed these guidelines, in the context of a larger discussion on the physical health consequences of isolation, there were a number of audible gasps across the room. Many of the people present had been fighting to end the use of long-term isolation in prisons and jails for decades, and here was this rule that is more direct, more humane, and more respectful of the dignity of living creatures than any policy for human prisoners anywhere in the country.

For mice.

Solitary confinement – the isolation of people for 22-24 hours per day without meaningful social interaction – can amount to torture, according to U.N. Special Rapporteur on Torture Juan Mendez. Yet it is one of the most common forms of punishment in our state and federal prisons and jails. Prisoners are generally denied access to books and other material that can mitigate some of the worse effects of isolation. They are almost always denied access to group religious worship or counseling sessions. In many cases, they are even denied access to necessary health care.

Here in Maine, we have made significant improvements in the way long-term isolation is used in our state prison: there are fewer people in solitary; they spend shorter amounts of time in isolation; and the conditions within the solitary unit are designed to mitigate some of the negative health effects. But, as a recent Frontline documentary clearly showed, we still have a long way to go. We haven’t achieved the gold standard yet; we haven’t even achieved the mice standard.

Maine’s solitary confinement reforms – and those carried out in Colorado, New York, and Washington state – serve the critical purpose of showing that prisons can protect the safety of staff and prisoners without relying on solitary confinement as the answer to every management challenge. Ongoing litigation in Mississippi, Arizona, and California has the potential of bringing even more prisoners under the protection of the Constitution’s prohibition on cruel and unusual punishment.

It has been said that you can judge a society by how well it treats its prisoners. America should be judged wanting in this respect, but we have the opportunity to improve our case.