For conscious shoppers at Whole Foods, it was a nightmare to learn that the company had US prison labor in its supply chain. After more than a year of negative publicity culminating in protests outside of its stores in Houston, Texas, Whole Foods announced last week that it will stop sourcing foods that are made with prison labor. Happy ending? Not so fast.

Corporations like Whole Foods need to be held accountable for the human rights abuses facilitated and supported within their supply chains. In the US market of prison labor, however, consumers should be aware of who extracts the lion's share of value from prison labor: federal and state governments.

The model of prison labor highlighted in the Whole Foods story involves a government-owned, corrections-operated organization partnering with for profit businesses in the production of a product or service. Corporations and industries involved in this kind of supply chain are many, and include the automotive industry, garments and as this story demonstrates, grocery products – even those of the "artisanal" variety.

However, the far more common versions of prison labor come in the form of in-house manufacturing, where the products or materials manufactured by incarcerated workers are sold to other government entities (such as schools, government offices, the military) or "big house" work, where prisoners are put to work in jobs that support the upkeep of the prison, such as running the kitchens, doing building maintenance or janitorial work.

Consider that, in the United States this labor can legally be completely involuntary and uncompensated. Refusal to work can and does come with harsh punishment. And wages, if paid at all, are far below minimum wage for the same jobs held by workers on the outside. – The Guardian, Oct. 7, 2015

Abraham Lincoln, while no friend of liberty in other respects, at least ended slavery in the American South. That was a century and a half ago. Now another form of slave labor has become common. We don't see it or think about it because it hides behind prison walls and enslaves an unpopular category of human. It is slavery nonetheless.

One could argue, of course, that making prisoners sew leather goods or build furniture is just punishment for whatever offense landed them in prison. It is far easier than the "hard labor" performed by prisoners in an earlier age. True enough, but three points reveal the injustice of modern day prison slavery.

First, many of the prisoners being forced to work are in prison for conduct that should not be criminal. Non-violent drug possession accounts for many. Others find themselves in the Big House due to irrational mandatory sentencing laws or prosecutorial overreach. These people should not be in prison at all and certainly don't deserve enslavement.

Second, forced prison labor is inconsistent with due process of law. Judges and/or juries determine guilt and assess punishment in an open, adversary process. Allowing prison wardens to mete out additional punishment in a closed, one-sided process makes a mockery of the supposedly impartial judicial system.

Third, prison labor directly enriches private parties like Whole Foods Market by letting them buy goods at artificially low prices. It creates a profit motive where none should exist. If private parties stand to gain from a higher prison population, they will naturally try to create one by whatever means they can.

Thankfully, consumer pressure convinced Whole Foods this practice is bad for business but The Guardian explains how it remains common. Will public shaming end prison slavery? Only if the public sees it as a problem. That may not be the case. Whole Foods customers are not the same as, say, Wal-Mart customers.

If low prices are the main priority, and free prison labor makes the low prices possible, many consumers will shrug and keep filling their carts.