Many companies seek captive markets—those in which consumers have little choice, like food in a sports arena or cable access in a rural area. But the ultimate captive market is the United States criminal justice system, where consumers are captive in both an economic and a physical sense.

Traditionally, private companies providing services in prisons have focused on food and personal items, as well as phone calls. These items are often priced at rates incarcerated consumers deem inaccessible—think $21 for a cheeseburger and wings, $31 for a hygiene essentials kit, or $15 for a 15-minute phone call (no small cost when you're earning an hourly wage of between 33 cents and $1.41).

Now, many private companies are expanding to sell digital services to incarcerated people and their families. As they do so, companies break into a market with little existing regulation—which, some argue, leaves room for exploitation.

While most commerce within prisons revolves around food and hygiene products, a Prison Policy Initiative report on prison commissaries, published in May, found that digital sales are the "future of commissary." The report also argues that digital sales serve as a new way to "shift the costs of corrections to incarcerated people" by monetizing opportunities for communication, education, and entertainment.

Read the full article about digital services in prisons by Mia Armstrong at Pacific Standard.