For more What in the World, watch GPS, Sundays at 10 a.m. and 1 p.m. ET on CNN

By Global Public Square staff

We were struck by a piece of news recently that is good for America, shows that our politicians are learning from their mistakes, and are actually cooperating with each other – on both sides of the aisle. Sounds too good to be true?

For many years, the United States has had a growing problem in its criminal justice system. As Global Public Square has pointed out before, the United States is number one in the world when it comes to incarceration – by far. In 2009, for example, for every 100,000 citizens, 760 Americans were in prison. That was five times the rate of incarceration in Britain, eight times the rate in Germany and South Korea, and 12 times the rate in Japan.

This trend began about 40 years ago. In 1970, state prisons had a combined total of 174,000 inmates. By 2009, they had 1.4 million – an eight-fold increase. And these correctional systems cost a lot of money of course – nearly $80 billion a year, more than the GDP of Croatia or Tunisia.

Well it seems that finally, common sense is prevailing. Attorney General Eric Holder made an important speech this week admitting that our prisons are overcrowded and costly. He specifically called for a reduction in mandatory sentences for low-level drug offenders.

It's important the attorney general brought up drugs, because the numbers are startling. Federal prisons, the group Holder was referring to, account for about 14 percent of our total inmates. In these prisons, the most serious charge for nearly half of all inmates is a drug offence. Compare that with state prisons, where only 20 percent of the inmates have a drug offence as their most serious charge.

More from CNN: Shame of mandatory minimums

Now, here is what is interesting. The federal prison population has increased every single year since 1980. On the other hand, state prison populations have been declining in recent years, so much so that the overall number of inmates – state plus federal – is actually down in each of the past three years. And here is the best part: the declines encompass 28 states, red AND blue.

Part of these declines are because budgets were simply collapsing. But it could also be because of a growing acknowledgment that the war on drugs has failed. According to the pro-reform Drug Policy Alliance, the United States spends about $50 billion a year on the drug war – adding up to a trillion dollars in the last four decades – but there has been no real change in addiction rates.

Americans are not more prone to drugs or crime than citizens of other countries, so why should we put so many people in prison? Well, the good news is that the numbers are finally too large to ignore. The states are already acting. And Holder's comments will add momentum to a growing chorus for reform.

The greatest challenge in pushing these numbers further down will be the prison lobby. Believe it or not, many of our prisons are run by private companies that then lobby state legislatures massively for bigger prisons, larger budgets, and of course more prisoners. According to the non-profit Justice Policy Institute, the two largest private prison companies in America together generate revenues of $3 billion a year – paid by taxpayers, of course. These private prison companies also happen to be major donors to a number of state campaigns, lobbying for more resources.

If our politicians can take on the prison lobbies, there really is hope for America.