-26 the authority to directly terminate it. The reality of prison regulations and prison life shows that regulations do not always prescribe visits from medical staff, that prison doctors are often not aware of their obligation to daily visit detainees, or of the possible effects of solitary confinement. Because they are warned of the possible dangerous nature of detainees or because of other reasons, often visits from medical practitioners take place from behind bars or from outside the steel door; at times prisoners, to avoid being visited in this way, directly refuse the visit. The trust between doctor and patient can also be broken in those cases when the doctor is part of the disciplinary committee and has a saying in the decision of the placement of a detainee in isolation, which should never be the case. Another issue is the risk of medical staff growing accustomed to prison operations, and feeling obliged to agree with the prison administration, or to mistrust detainees reporting health issues because of the fear of being used by them. This is also where NPMs could help to build a common culture among prison staff in different areas of expertise. 2.3. Solitary Confinement as a cultural issue The excessive use of isolation is a legal problem but also the product of a widespread culture. As far as legislative shortcomings are concerned, the NPM can influence lawmakers to address the gap between national legislation and international standards. However, only in some residual cases is the problem just legal. In fact there can be grey areas where the decision of the prison warden, informal laws or prison customs apply instead of the State’s penitentiary law. The consequences of the existence of grey areas may include the violation of the minimum standards on detention conditions on solitary confinement, the lack of a review mechanism, high levels of violence and a great discretionary power of the prison warden. The possibilities of action of the NPM are also within these extra-legal areas. 2.3.1. Lack of a common legal ground in the prison staff In different countries, among some staff members, internal regulations (secondary legal sources) are considered more binding than international