“America’s prisons and jails now house some 2.2 million inmates – roughly seven times the figure of the early 1970s. For years sociologists saw prisons – with their disproportionately poor, black, and uneducated populations – partly as mirrors of the social and economic disparities that cleave American life. Now, however, a new crop of books and articles are looking at the penal system not just as a reflection of society, but a force that shapes it.”