The U.S. policy of punishing the poor has been recently taken on by state legislatures passing laws requiring recipients of public assistance to submit to drug testing. This was implemented, before it was suspended, in Florida where a Federal court ruled that it was an unwarranted violation of personal privacy. Further, the evidence from the brief duration of the program found lower rates of drug use among the targeted poor than the general population.
Of course, this has not stopped other states from trying to stigmatize the poor. The current case is Minnesota, requiring counties to randomly drug test individuals who receive welfare benefits despite the evidence from similar programs and the fact that local officials believe it is a waste of time and will end up costing taxpayers more rather than less.
The most sophisticated analysis of this general movement in social policy can be found in the work of sociologist Loic Wacquant in Punishing The Poor: The Neoliberal Government of Social Insecurity and in recent shorter pieces where he makes the argument below:
The linked stinginess of the welfare wing and munificence of the penal wing under the guidance of moralism are profoundly injurious to democratic ideals. As their sights converge on the same marginal populations and districts, deterrent workfare and the neutralizing prisonfare foster vastly different profiles and experiences of citizenship across the class and ethnic spectrum. They contravene the fundamental principle of equality of treatment by the state and routinely abridge the individual freedoms of the dispossessed.