Even with this classification, we have to be careful in the liberties given to these inmates, because classifications are made not only by crimes committed, but also on space available in other prisons and expediency in terms of the courts. The last and most dangerous type of prison is maximum security. This is where the worst and most uncontrollable inmates are housed. In this type of setting both exterior and interior security have high priority. The outside perimeter might have more than one layer of fencing and such security measures as armed guard towers, searchlights, and electronic detection devices.
Interior security focuses on knowing where a prisoner is at all times.
Movement in these institutions is tightly watched, visitation is limited and carefully scrutinized, and inmate counts are taken several times daily. Even with such security measures these facilities are not safer for the officer, since such tight and extreme measures often make inmates more frustrated and thus more dangerous. Another major problem that endangers an officer as well as the prisoner population in general is the number of inmates. The United States now has the highest incarceration rate of any country in the world. With these problems comes a change in the attitude of the average prisoner which in turn affects correction personnel in their daily duties.