From the article:<p>&gt;The offenses that landed them in solitary? Most often, it was evidence that they were &quot;affiliated&quot; with a prison gang, whether or not they had broken any rules.<p>Solitary isn&#x27;t being used as a last resort for people who have killed previous cellmates -- it&#x27;s being used for all sorts of things.<p>I think solitary makes sense for people who are already unable to coexist with other inmates, but that doesn&#x27;t seem to be the main use at the moment.