Protective custody can be hard for the uninitiated to design and run. It is not explained in the early game, and there is next to no advice in-game on how to do it (in contrast with most other game mechanics). Every prison architect, at some point, has lost a Snitch, Ex Law Enforcement, or Ex Prison Guard at some point (often frustratingly an inmate whose reputation was previously unknown), but these deaths can be avoided even early in the life of a new prison. This guide aims to provide sound advice on how to use this feature well.

Protective custody is a prisoner grading that can be assigned to a prisoner in their profile. It is separate from the usual hierarchy of security grading.

Protective custody is designed to allow you to separate out inmates who may be at serious risk of violence from others. It can also be used in any way that you wish (including to try to prevent dangerous inmates from causing violence to others), but this is at your discretion, and is probably better achieved with the normal security grading system.

It is generally considered wise to segregate protective custody inmates as much as possible. This requires forward planning and some inefficiency in your prison design, but comes with many benefits.

• Those with relevant traits will be attacked randomly by other inmates. Inmates often gang up on snitches and those with ex-enforcement traits, and will fight to kill.
  
• Cop Killers are at high risk from your guards. If they cause any trouble at all, they may be killed by your guards (whereas other inmates would simply be beaten until they stopped resisting), another major source of death. It is best to keep these inmates in places where they never cause trouble in the first place.
  
• All deaths dramatically reduce prisoner perception of safety, which further increases violence and overall prisoner needs. Deaths may contribute to failure conditions. Deaths reduce your income, reduce the prison valuation, and may reduce your prisoner intake.

No inmate arrives in the prison with the protective custody designation. You will have to screen new arrivals and manually assign this for each inmate for whom you think it is relevant.

The following traits mean that an inmate should always be assigned to protective custody:

• Snitch
  
• Ex Law Enforcement
  
• Ex Prison Guard
  
• Ex-Gang Member (if you have a relevant DLC)
  
• Federal witnesses (if you have events turned on)

All of these groups will be attacked on site by inmates or even staff. Importantly, merely being in protective custody does not put inmates at risk: only their reputation does.

You may also consider putting those with unknown "???" reputation into protective custody until you know what their traits are. This is generally wise, as many (but not a majority) of these inmates may turn out to have a relevant trait that puts them at risk. This is a challenging dilemma, as including these people in protective custody may double or even triple the size of the protective custody wing that you need. A general exception will be gang members, who are highly unlikely to have any at-risk traits even if their remaining reputation is unknown.

You may also consider putting your highest risk inmates into protective custody. This makes them easier to track around the prison. Additionally, many legendary prisoners may be gang leaders or lieutenants (who are at high risk of being attacked by rival gangs).

The benefit of assignment is that you can segregate inmates appropriately, spot them more easily with "Informants" in "Intelligence" (as the default colour is an obvious yellow that is easy to spot), and protect your staff.
The drawbacks of protective custody are limited but not non-existent. Protective custody inmates may not pay any daily money and so you lose out on this income - not every inmate can be in protective custody, and it is best to move people out of protective custody if they no longer need it (for example, an inmate with unknown traits has those traits discovered and they are low-risk).

Commissioning is preparing a product or service that had a significant lead time (like a building) ahead of when you need it. In this instance, you do not know exactly when new inmates who need protective custody will spawn (either by newly arriving at the prison or by having the "Snitch" trait added), so you need to be prepared.

You will need to commission protective custody services bearing in mind a few core characteristics of your prison, and how much surge capacity you will need.

• On admission to the prison, certain security gradings are more likely to have traits that benefit from protective custody. The highest percentage is associated with medium security, with the lowest percentage associated with maximum security and SuperMax security (Death Row inmates and the Criminally Insane cannot be transferred, and will never have relevant traits). Build your protective custody to the right size based on this.
  
• If you have "Events" enabled, and you (like most prison architects) choose to employ confidential informants (CIs), bear in mind the random event of "CI List Leak", which is about as bad as it sounds. Everyone on the list will gain the trait of "Snitch", and should be put into protective custody. You probably can't build your protective custody wing to be big enough to handle this, but you should have a little extra slack the more CIs that you have.
  
• It takes time to discover the traits of prisoners with unknown traits. If you are expanding the prison rapidly, you will end up with a higher proportion of inmates with unknown traits, leading to a greater need for protective custody. If you are accepting a large number of inmates (my guide would be more than 20 inmates) into the prison in 1 batch, always make sure that you have a few spare spaces in your protective custody wing.
  
• If you are not able to tap phones or visitation booths and / or you have no CIs, you will not be able to quickly discover the reputations of inmates with unknown reputations. If they are assigned to protective custody, they will likely have to stay in protective custody for much longer, and so you will need a larger wing to accommodate them.

Protective custody benefits from segregation of facilities. Facilities can be segregated spatially (different buildings) or temporally (by the schedule). Spatial segregation is more expensive and harder to staff, but also more reliable and a much safer option. Temporal segregation is cheaper and simpler, but also means more mixing of protective custody inmates with the general population.

Certain facilities are more important than others, based both on the frequency of usage and based on the risk of the equipment and contraband in these areas:

• Canteen. All inmates must use this (unless in lockdown), prisoners congregate in large numbers, and prisoners have access to cutlery. This is a high-risk area for at-risk inmates, and must always be segregated (preferably spatially).
  
• Common Room / Yard. Mot inmates use these areas on a daily basis. Contraband risk is lower here, but this remains a higher-risk area, and should preferably be spatially segregated.
  
• Parole Room / Visitation. These areas are important for prisoner rights and meeting needs, and may represent locations where protective custody inmates are at higher risk (as it is hard to temporally segregate these). This will generally require spatial segregation.

Another form of segregation can be achieved by assigning protective custody inmates to permanent lockdown, but this is suboptimal for many reasons, and will lead to prisoner violence and injury.

• All protective custody inmate should have a separate cell. If you decide to place protective custody inmates amongst your general prison population, make sure that they cannot be placed in dormitories.
  
• Make protective custody cells nicer than the prison average. These inmates will have reduced access to shared spaces to meet their needs, so need more of their needs met by objects in their own cell
  
• Protective custody wings should preferably be under 1 roof, with all of the core facilities (particularly the Canteen and the Common Room) located without an arduous commute.

• To quickly elicit the traits of inmates with unknown traits, use all 3 key methods: tap the telephones; tap visitation (requiring visitation booths rather than tables); hire CIs and use them (requiring use of solitary confinement).

• Keep protective custody inmates well-guarded. Other inmates may try to access it to attack the inmates there, particularly during riot situations. Additionally, some of your inmates with unknown traits will try to attack other protective custody inmates (although it is rare for those with at-risk traits to attack others). Armed guard is helpful for this.
  
• Provide inmate jobs on the wing. This is easiest with the "generic" jobs like "Laundry Room", "Cleaning Cupboard", and "Kitchen", although you can expand this to others such as "Library" and "Shop". This maximises the spatial segregation of protective custody inmates.

Protective custody requires intervention to work well. You will need to manually screen all admissions to the prison to assign them to protective custody. It is easy to miss important labels, especially if labels are covered up by those of other inmates when they arrive to the prison. You will also want to move those with low-risk traits back to their appropriate security level once unknown traits are discovered.

Keep a close eye on your protective custody inmates. Make sure their needs are met in particular, as they are at high risk of their needs not being met due to the nature of their segregation.