How does the US criminal justice system create and maintain racial hierarchy through mass incarceration?

The authors note that we are loath to speak about caste and race in the United States, and we also have the myth that social mobility is possible. That is, we believe that people can move up the class scale based on their efforts.
However, the authors point out that a large proportion of African Americans cannot move up the class ladder. They are facing a lack of educational and other opportunities, as well as poverty. In addition, they are prohibited by law from moving up economically and socially because of their involvement in the criminal justice system. As a result, they cannot participate in the social and economic life of the country. The criminal justice system creates and perpetuates a continual underclass in our country of people who have been or are incarcerated. The authors write that the criminal justice system has an interconnected set of customs, laws, and institutions that maintain an underclass based primarily on race.