It is also worth noting that studies suggest that solitary confinement is not an effective tool for managing those defined as ‘problem’ or ‘difficult’ prisoners and may even be counter-productive. A study of the ‘incorrigible units’ in North Carolina in the late 1950s, where prisoners were subjected to a regime of strict and prolonged solitary confinement, concluded that “the over-all impact of the incorrigible unit in penal practice probably is one that intensifies tendencies to criminal attitudes and behavior” (McCleery, 1961:306). Other studies identified isolation regimes as central factors leading to prison riots. One study of events leading to the 1980 riot in the New Mexico Penitentiary (USA), for example, attributed the riot directly to the strategy of isolating prisoner leaders, which led to the fragmentation of prisoner solidarity and in turn led to growing violence. A study of ‘order and discipline’ in prisons in England and Wales concluded that “to impose additional physical restrictions, especially of a severe character, will almost certainly lead to a legitimacy deficit; and that deficit may well in the end play itself out in enhanced violence” (Bottoms, 1999:263). Similar findings emerge with regard to the isolation of gang members. One study found that the policy of placing gang members in solitary confinement in special security units in California led to an increase in gang activity, as “prison authorities’ efforts to contain the spread of gangs led, unintentionally, to a vacuum within the prison population within which new prison groupings developed” (Hunt et al. 1993:403). Leadership struggles among these new groupings then resulted in gang related murders in general population prisons (Parenti, 1999:209). Data on prison violence before and after the introduction of special security (or ‘supermax’) units, similarly indicates that the isolation of prisoners classified as dangerous or disruptive did not result in a reduction of prison violence in general population prisons41. In short, though solitary confinement may be a convenient tool for managing challenging prisoners in the short term, in the long term it is not effective, and may prove to be counter-productive. Further, as Chapter Two illustrated, prolonged solitary confinement may have very serious health consequences for the individual concerned and may also affect his chances of successful reintegration into society. Every effort should therefore be made to reverse the trend towards supermax prisons and similar regimes which are wholly based on solitary confinement. Where it is absolutely necessary to hold a handful of extremely dangerous prisoners in separation from others, there should be ongoing assessment of the need to keep them isolated, and they should be afforded increased in-cell provisions, access to programmes, opportunities for meaningful human contact and so on. 32 Sourcebook on solitary confinement: The decision to place prisoners and detainees in solitary confinement