Banning the homeless from sleeping outside when they have nowhere else to sleep is unconstitutional, argues the United States Department of Justice in a statement of interest filed regarding a Boise, Idaho court case about an anti-camping ordinance.
According to the DOJ, such ordinances may violet the US Constitution's Eighth Amendment, prohibiting cruel and unusual punishment. From the DOJ filing:
When adequate shelter space exists, individuals have a choice about whether or not to sleep in public. However, when adequate shelter space does not exist, there is no meaningful distinction between the status of being homeless and the conduct of sleeping in public. Sleeping is a life-sustaining activity—i.e., it must occur at some time in some place. If a person literally has nowhere else to go, then enforcement of the anti-camping ordinance against that person criminalizes her for being homeless.