Tracking Procedural Justice in Processing Detainees: Coding Evidence from CCTV Cameras in Three Police Custody Suites

How closely do custody suite encounters between detainees and custody suite officers (CSOs) match the procedural standards for decision makers treating people who are subject to their authority? To what degree does measurement of procedural justice displayed by CSOs on closed-circuit television (CCTV) records vary across detainees, CSOs and custody suites? Arrest records for July, August, and September 2020 across three custody suites in the East of England were obtained and a random sample of 150 encounters selected for analysis. Encounters between CSOs and detainees at the booking-in stage as captured on pre-recorded CCTV were coded into four elements of procedural justice: voice, trustworthy motives, impartiality, and respect. Non-verbal communications and dialogue were also examined. Overall, custody suite officers demonstrated high levels of respect and neutrality in dealing with detainees. However, they showed relatively less care for the wellbeing of the detainees and did not offer them enough opportunities to ‘tell their side of the story’ (‘voice’). Further analysis revealed statistically significant variations across the three custody suites in the level of opportunities offered to detainees to have an input in discussing the decision-making. We also found evidence that as length of service as police officers and in custody roles increased, the observed level of expression of ‘trustworthy motives’ displayed decreased. Finally, detainee compliance with officers was greater when respect and care for the wellbeing of detainees were more pronounced. A tracking study can help identify police units and police officers with greater concentrations of procedural justice deficits. Such evidence can support more targeted training to improve the delivery of procedural justice, and enhance public confidence in policing.


Introduction
In 2014, the Independent Police Complaints Commission ((IPCC, 2014), now called the Independent Office of Police Conduct) produced a report on police contact and response to calls following the murder of Mr Bijan Ebrahimi, an Iranian refugee living in Bristol, England. He had called the police several times to report racial abuse and threats to his life by his neighbours. One of his interactions with the police was at a custody suite and captured on custody a closed circuit television (CCTV). An officer told him not to talk to her, that she was not talking to him, she did not want to hear anything he had to say: 'I can't even be bothered to waste my energy on you' and he should 'just smoke and stay quiet'. When he suggested that she was his friend, the officer retorted that she was a police officer and "you're a pain in the ass. Don't speak to me." (IPCC 2014, p.40). The case of Mr Ebrahimi is not an exception; there have been other incidents of inappropriate treatment of detainees in custody, sometimes with fatal consequences.
The issues raised in Mr Ebrahimi's experience connects with the broader criminological work on legitimacy. Legitimacy refers to police power that is recognised as morally valid (Beetham, 2013;Tankebe 2012, 2017). Among the key foundational building blocks is procedural justice. Procedural justice refers to people's subjective experiences of the quality of interactions they have with powerholders such as police officers. It is a multi-dimensional judgment comprising concerns about respect, neutrality, trustworthy motives, and participation. When people feel poorly treated during everyday interactions, it undermines their views and relationships with the authorities (Mazerolle et al., 2013;Jackson et al. 2012). As Tyler (6: 257) put it, 'every encounter that the public have with the police, the courts and the law should be treated as a socializing experience that builds or undermines legitimacy. Each contact is a 'teachable moment' in which people learn about the law and legal authorities.' Skinns and colleagues describe custody as the "ultimate place" for such teachable moments, with custody staff often using their authority "softly and innocuously" to induce compliance (Skinns et al., 2017: 601).
Studies of procedural justice have often drawn on data from the general population to examine its effects on people's feelings of obligation to obey the police and to cooperate with them (Tankebe 2019;Sunshine & Tyler, 2003). Other studies have focused on surveys of known offenders (Augustyn 4;Paternoster et al., 2015;Papachristos et al., 2012) while others have explored the experiences of victims (Murphy and Barkworth 2014;Tankebe, 2013). Rather than a reliance on people's accounts of their experiences, some researchers have undertaken systematic observations of police-citizen interactions (e.g., Worden and McLean 2017;McCluskey et al., 2019). However, such studies struggle to overcome the well-known Hawthorne effect. Video recordings of police work offer an opportunity to overcome this effect. Thus, Nawaz and Tankebe (2014) studied procedural justice of stop and search by reviewing interactions captured on police body-worn cameras.
The current study extends this methodological innovation to police custody suites by coding evidence from CCTV of custody encounters between custody suite officers (CSOs) and detainees in three very different custody suites in England 1 3 (UK). The study aims to answer the following questions: How closely do custody suite encounters between detainees and custody suite officers match the procedural standards for decision makers treating people who are subject to their authority? To what degree does measurement of procedural justice displayed by CSOs vary across detainees, CSOs and custody suites? How does procedural justice measured by CCTV coding relate to use of force and detainee compliance? Is there a correlation between PJ scores and the age and length of service of CSOs?

Data and Methods
This is a correlational study which simply observes "the size and direction" of the relationship between different variables (Shadish et al., 2002, p.12). The data for the study came from 3 months of CCTV recordings (June to August 2020) at three police custody suites used by Cambridgeshire Constabulary, two within the County, Cambs North and Cambs South, and one outside it in Norfolk. Police custody suites in England and Wales are subject to unannounced inspections by Her Majesty's Inspectorate of Constabulary Fire and Rescue Services (HMICFRS) and Her Majesty's Inspectorate of Prisons (HMIP) who check that detainees are treated in accordance with Article 3 of the Human Rights Act 1988. This states that 'no-one shall be subjected to torture or to inhuman or degrading treatment or punishment.' All three of the custody suites included in this study were assessed as "good" in 2018 when they were last inspected.
The selection of the 3 months for the study was not random. It was dictated largely by the availability of the CCTV footage. However, the selection of the encounters during that period was randomised, giving each encounter an equal chance of being included. The use of CCTV-recorded data overcomes limitations in body-worn recordings. The latter relies on cameras being activated by officers, hence can sometimes fail to capture crucial phases on encounter. Custody CCTV, on the other hand, is constantly recording, meaning the whole of the booking-in process interaction is captured. However, interactions leading up to the detainee being brought to the booking-in desk were not captured. This made it impossible to determine how pre-custody interactions might have influenced detainee behaviour at the custody suites.
Thirty-five custody suite officers worked at the three suites full time. They authorised the detention of detainees 2402 times over the three months. A complete sampling frame of interactions was developed for each site. We then selected 50 interactions each, making a grand total of 150. Thirty-four of the 35 CSOs were chosen through this method. Due to the low throughput of Cambridgeshire detainees at the Norfolk Police Investigation Centre used in this study and the fact that only two of the CSOs were female, all the records at that custody suite with a female CSO for the 3-month period were coded.

Voice
Five questions were used to elicit whether the detainee had been allowed to express their views by asking for information, being allowed to respond without being interrupted or rushed and whether the CSO appeared to be interested in what they had to say. When coding for "the officer gave the detainee a chance to ask questions" this was only coded "yes" if the CSO asked the detainee if they had any questions. This was because most of the booking-in process involves the CSO asking for yes or no responses to complete a risk assessment. A CSO saying, "let me know if you have any questions, I know it can be a bit daunting" was scored "yes".

Trustworthy Motives
Answers to the seven questions in the element, "trustworthy motives", captured whether the CSO was motivated to do what was good for the person (Jonathan-Zamir et al., 2015). This included the CSO explaining why they were authorising detention and explaining the purpose of the custody process, supported by comments made like, "we will look after you". One of the first questions CSOs tended to ask a detainee was whether they had been in custody before. If the answer was "yes" or they recognised the detainee, these explanations were likely to be missed. If the CSO did not state that they were authorising detention and the reason for doing so, it was coded "no". There was sometimes banter between the CSO and detainee; whilst this showed good rapport building it tended to distract the CSO from the booking-in process.

Respect
The "respect" and dignity element comprised six questions, including questions about whether the CSO was polite and courteous and used words and a tone which were respectful. Answers to these questions were coded on a Likert-type scale using the coder's judgement.

Neutrality
This contained five questions and was the most difficult element to code as it relied on the researcher observing subtle differences in treatment to confirm that decisions comply with the rules and are reasoned and objective (Skogan et al., 2014). The researcher observed a CSO recommending that detainees exercise their right to have a solicitor and saying, "I'm not just saying this to you, I say that to everyone", which he did. One of the constructs for neutrality stated, "the officer used protocols/rules in a consistent way for every detainee." As this could not be scored until the CSO had been observed at least once it was later excluded from the combined procedural justice score for this element.
It took approximately 30 min to review and code each encounter into the four key elements of procedural justice -voice, trustworthy motives, respect, and neutrality and capture the additional qualitative data.

The Coding Process
Consistent with Jonathan-Zamir et al.'s (2015) approach, the coding assigned no special weight to any specific item or component, treating them all as equally important. All items that were measured using a scale were re-coded into a binary score. For example, if an officer was dismissive, inattentive, or passive they were given a score of 0, and 1 if they showed an active interest in what the detainee had to say. Four of the constructs for "respect" were coded 0 for "not at all" and 1 if respect was shown some, most or nearly all the time. In addition, some of the binary measures had to be altered prior to analysis so that they were consistent. For example, "the officer gave the detainee a chance to ask questions" 0 = no, 1 = yes and "the officer rushed or interrupted the detainee" was changed so that 0 = yes and 1 = no.

Findings
We begin with Kendall's tau correlations between time of day of the interaction, officer current age, joining age and length of service, and each of the individual elements of procedural justice. The results are presented in Table 1. First, trustworthiness and voice were the only elements of procedural justice to show a consistent correlation with CSO demographics; specifically, trustworthy motives decreased as experience in CSO role (Kendall's tau = -0.2, p < 0.01) and as a police officer increased (Kendall's tau = -0.2, p < 0.01). Research by Nawaz and Tankebe (2018)  found that the level of procedural justice displayed was greater at night, including the explanations officers gave and the feeling of neutrality. In the current study, 78 of the coded encounters took place in the daytime, defined as being between the hours of 0700 and 1700, and 72 were carried out at night. In this analysis, we found that officers demonstrated more voice during night-time than during the day (Kendall's tau = 0.2, p < 0.05)). They also showed greater neutrality during the night (Kendall's tau = 0.2, p < 0.05) but were less respectful (Kendall's tau = -0.2, p < 0.05).
Officers who are neutral are more likely to offer detainees a chance to be heard and give them the opportunity to ask questions (Kendall's tau = 0.3, p < 0.01).

Overall Rating on Dimensions of Procedural Justice
This section has two broad aims: first, to present the total scores for each of the four dimensions of procedural justice -voice, trustworthy motives, neutrality, and respect -and to explore how these vary across the three custody suites. It also explores overall procedural justice scores for the suites. The second aim is to strengthen the quantitative data by drawing on qualitative data to discuss each of the procedural justice dimensions.
To achieve the first aim, a score was computed for each of the dimensions. Voice and neutrality had a maximum score of 5, respect had a maximum score of 6, and trustworthy motives had a maximum score of 7. The mean for each element was calculated as a percentage of the total possible score. Figure 1 shows that neutrality was the highest scoring element, followed closely by respect. Trustworthy motives and voice attracted lower scores, but the lowest scoring element still achieved a score of almost 70%.
In terms of the overall procedural justice score for each of the custody suites, the evidence shows parity across the suites, with scores ranging between 84% at Norfolk and Cambs North and 86% at Cambs South. Figure 1 presents the scores for PJ elements across the three custody suites. The data show that CSOs at Norfolk scored lowest for trustworthy motives (73%). Those at Cambs North had the lowest score for voice (65%). There was only a marginal difference between the level of respect and neutrality shown at each of the three custody suites. A Kruskal-Wallis H test showed the custody suites differed only in the level of voice displayed χ 2 (2) = 12.9, p = 0.002., with a mean rank score of 84.4 for Norfolk, 59.3 for Cambs North, and 83.8 for Cambs South (Fig. 2). We now turn to the second aim for this section, which offers more context for each PJ element.

Voice
CSOs who scored highly for the element of voice made comments such as: "Have you got anything to add?" when they had completed the risk assessment process, while another said, "If you've got any questions then just ask". One CSO said, "Let me know if you have any questions, I know it can be a bit daunting" to a detainee who had not been in custody before. Some CSOs were observed to specifically ask the detainees if they had any questions and gave them the opportunity to ask them. This was the case most at Norfolk, in eighteen interactions, then at Cambs South, at fourteen and the least at Cambs North, with only nine.
CSOs whose score for voice was low included those who rushed or interrupted the detainee. One detainee said, "What, attempt murder?" when the officer was relaying the arrest reason to the CSO. The CSO responded by saying, "Let him (the arresting officer) speak please". Another CSO rushed through the questions in the risk assessment, giving the detainee very little time to respond to them. One detainee said, "How long am I going to be here for?" and was told to "shush". These negative interactions were observed more frequently at Cambs North than at the other two

Trustworthy motives
There was clear evidence that over half the CSOs observed were motivated to do what was good for the detainee and displayed trustworthy motives, particularly at Cambridgeshire's custody suites. This reflected the results of the coding, which showed CSOs at Norfolk scoring lower for trustworthy motives. Officers made comments to show that the detainee was going to be cared for during their time in custody: "We'll look after you", "If you start to feel unwell, you'll need to let us know". Another said, "We will make this as quick as possible", asking, "When did you last get any sleep?" In one instance, a detainee asked, "If I feel anxiety in your cell what do I do?" The CSO replied: "You need to tell us". Another CSO took the time to ask an immigration detainee how long he had been travelling from his home country, reassuring him that he would be placed in a cell but would be safe. Where detainees were claustrophobic or anxious about being placed in a cell, CSOs arranged for them to have someone sit with them or to go into a cell with a glass door. There were good explanations about how things worked, like cell buzzers if a detainee needed something and explanations about what would happen to them: "When you are sober you will be able to go back to your Mum-if we get you sobered up quickly you can leave". There was also ample evidence of CSOs getting medical help for detainees when needed, with a CSO getting a medic to come to the desk to see someone who said they felt unwell. Another asked what happened to a detainee's eye and if it hurt and got a medic to check it straight away, which resulted in the person going to hospital.
One CSO said to a man who had been arrested for an alleged sexual assault: "These are not very nice allegations to have said about you, I would be feeling devastated too", and when asking if the detainee had taken any drugs in the last 24 h said, "I'm not trying to trick you". They explained, "What will happen now is my colleague will do your hand swabs and then we will get you a drink and make you as comfortable as we can".
Less positive interactions sometimes took place where there was a history between the CSO and the detainee. One CSO told the detainee to get back from the desk, saying, "Last time we ended up putting you on the floor, you're the making of your own issues really".
There was a good use of humour between CSOs and detainees, particularly at Cambs South. This can help build rapport and encourage compliance (Skinns et al., 2015). This included a CSO saying, "nice day for it too" when a detainee said that he had consumed five pints. Another said, "Don't be telling me stuff I'll have to keep writing", and another, "We're not going to lock you up and then go and have dinner, we will process you as quickly as possible, I can promise you that". One CSO explained to a detainee who spoke limited English that they would go to a virtual court, by saying, "Tomorrow morning, TV court here". Another CSO said, "It's not as exciting as the telly, is it?" When asking detainees their personal details one said, "6ft 4 in his best heels he is", and another, "Your eyes, they are red!" when checking their eye colour and "Poor you" when the detainee said that he was living in Wisbech.

Neutrality
Fewer observations were recorded for the element of neutrality, which scores for subtle differences in treatment. A CSO at Norfolk explained that he always advised detainees to have a solicitor as it was in their best interests: "I'm not just saying this to you, I say that to everyone," a fact which was observed in other encounters involving him. Other CSOs made it clear that they were impartial: "Just because you are here doesn't mean you are guilty, and I won't look at you like that." When a detainee said, "I'm really sorry guys", the CSO replied, "I'm not here to judge you". The researcher observed one CSO saying, "it doesn't sound like a lot has happened" to someone who had been arrested for a common assault and, "It will be a shame if you are over the limit, you seem like a really nice guy", to someone detained for driving with excess alcohol.
Generally, CSOs remained calm during the booking-in process, even where the detainee was agitated and shouting. This was seen with a CSO at Norfolk and a woman who was in custody to prevent a breach of the peace. The CSO explained she would be staying until she calmed down. Occasionally a CSO reached the end of their tether. One CSO said, "I'm not calling anyone, you had your chance", and ignored the detainee who had also been arrested to prevent a breach of the peace, when he said he could go to his daughter's. This detainee stood with his back to the CSO some of the time, prompting them to say, "Turn round, I'm talking to you". This sort of "parent-child" interaction was observed in other encounters. A CSO said, "You were only arrested a few days ago for theft of a motor vehicle", and proceeded to fold her arms when explaining why he had been arrested. As the detainee kept pulling his face mask down even when he was not speaking, the CSO told him to keep it on, saying, "I am wearing mine". A similar relationship was observed with a CSO and a man arrested for failing to appear at court when required to do so, with the CSO saying, "You could have just turned up at court, don't blame us, it sounds like you are". "I ask you a straight question, I expect a straight answer, are you listening to me", and when they asked to make a phone call responding with, "not right now, I'm booking you in". Another CSO said, "You haven't learnt, have you?" to someone who had been arrested for drink driving a second time. This detainee also stood with his back to the CSO, with his hands in his pockets and head down when answering the risk assessment questions.

Respect
There was some good evidence of CSOs showing respect to detainees and their rights, making sure they had an appropriate adult if they needed one, as "A good safety net for yourself", and could understand their rights and entitlements under PACE if they had learning difficulties or did not understand English. When a detainee said she had a hearing problem the CSO asked if she used sign language and said that he would arrange for an appropriate adult for them and go through their rights again when they were present.
A CSO said, "Some of these questions are quite personal, they are not designed to cause you any embarrassment", and another arranged for a female detainee to speak to a female officer away from the desk. A CSO at Norfolk gave a good explanation of how a solicitor would be involved if a detainee chose to have one, and another one took the time to explain the difference between being arrested on suspicion of an offence and being charged for one. Even when explaining that a particular right had been delayed, CSOs framed this in a way that was acceptable to detainees, with one saying, "You get an extra right if you are a non-UK National" but "The inspector has put a delay on your right to have someone told of your arrest, sorry about that".
Less positive observations of this procedural justice element included dismissive, sometimes rude comments like, "I've no idea what you are talking about", and "You're not making much sense about your pregnancy". One CSO asked, "Do you normally have an appropriate adult when you are here?", rattled through his rights and then when the detainee asked him to explain them said, "They are written here", although the detainee said he had difficulties reading. One CSO asked a detainee if she could read or write. She said, "Not really", and they replied, "You can get by though?" with no offer of arranging an appropriate adult for her. A couple of inappropriate comments were noted. One CSO said, "I'll tell you now being a twat is not going to help you in here", and "Just wind your neck in", but these comments were rare.
The use of telephone interpreters was seen to be problematic at times. One CSO said, "A panic attack won't get you out of custody, the longer you stay here the longer you are going to be in custody, I'm going to hang up now". Another detainee was denied his rights, with the CSO terminating the call with the interpreter and saying he (the detainee) was not listening.

Procedural Justice and Crime Harm
We computed the Cambridge Crime Harm Index (CCHI) score for suspected offences for which the individuals were arrested. Where the starting point for an offence is a set prison sentence the score is based on the number of days imprisonment. For those where the starting point is either a community sentence or a fine, it is based on the number of hours needed to complete the unpaid work requirement of the community sentence or hours needed to work to pay off the fine, rounded to the nearest whole day (Sherman et al., 2016). Six of the offences could not be scored as they do not appear on the CCHI-two for prison recall and four for breach of post charge bail.
As shown in Table 2, the mean CCHI value was highest at Cambs North (281 days); three offences that could not be scored. The average CCHI score was lowest at the Norfolk suite (89) which only had three high scoring offences -rape of a female child under the age of 16 and two incidents of arson endangering life. Table 3 shows that Cambs North was the highest harm custody suite for 'offences against the person' -comprising murder (5475 days) and two grievous bodily harm (1460 days) -with a total CCHI score of 8432 days. The score was also high at Cambs South (4418 days) but significantly lower at Norfolk (112 days). Cambs North (2196 days) and Norfolk (2219 days) were harm spots of criminal damage. Cambs

3
South was the harm spot for sexual violence (5571 days), theft (1130 days) and misuse of drugs (1095 days). In the category of sexual offences, it included three arrests for rape; for the misuse of drugs, the arrests included two for possession with intent to supply. The CCHI score for drug misuse at Cambs North was 558 days while Norfolk had no score at all. That custody suite had the highest score for harassment (62 days) and public order (22 days). The overall picture that emerged was that, in comparison with Cambs North and Cambs South, Norfolk was a relatively low-harm custody suite.
As shown in Table 4 below, there was no significant association between the level of procedural justice displayed for each of the four elements and the CCHI score, but as previously seen, there was a statistically significant correlation between neutrality and voice.

Detainee Compliance and Use of Force
Detainees who were uncooperative or violent were not included in this study as it would not have been possible to code the four elements of procedural justice for them. There were fourteen such cases. These were identified from custody record entries during the preparatory work for coding cases. This meant that most of the  detainees observed were compliant with no requirement for officers to use force against them, other than the use of handcuffs at the booking-in desk.
Compliance of detainees was coded either yes or no, depending on whether the detainee answered the CSO's questions and how they behaved. Fourteen detainees (9.3%) in the sample were coded as being non-compliant. Table 5 shows that there was a statistically significant correlation between compliance of a detainee and PJ scores for respect (Kendall's tau = 0.4, p < 0.01) and trustworthy motives (Kendall's tau = 0.2, p < 0.01).
One non-compliant detainee put the phone down on an interpreter and said she wanted a cigarette when asked if she had any medical conditions. A male detainee stood with his back to the CSO some of the time. One CSO was observed to only show respect some of the time to a non-compliant detainee who was being booked in via an interpreter on the telephone, saying, "We can waste many, many minutes of him telling me pointless things at the desk", and "If he is not going to engage in the bookingin process as I want to do it we can stop it again and do it in 4-6 h." One detainee was asked his name and replied "f**k you." Another detainee did not have a shirt on, was out of breath and agitated when first brought to the booking-in desk. He had been sprayed with PAVA (similar to pepper spray) and paced up and down and started crying when asked about self-harming but calmed down by the end of the booking-in process.
There were more non-compliant detainees at Norfolk (9) than at Cambs North (3) or Cambs South (1). A Chi-square test showed that there was a significant relationship between compliance of a detainee and the custody suite (Χ 2 (2, N = 150) = 7.72, p = 0.021). There were more non-compliant non-white British detainees (15%, n = 8) than white British detainees (5%, n = 5), but this was not statistically significant. However, there was a statistically significant correlation between the gender of the detainee and whether they were compliant, (r = − 0.18, p < 0.05), with 16% (n = 5) female detainees coded as non-compliant compared with 7% (n = 8) of male detainees.

3
In terms of use of force, which includes use of handcuffs, this was observed in 30 encounters. Only four of these were not linked to handcuffing. One involved a female detainee having her jewellery -necklace, rings, and earrings -removed by force as she refused to give them to the CSO when her property was being booked-in. Another involved officers moving a female detainee to keep her away from them and facing the desk. Two others involved the use of PAVA prior to the detainee arriving at the booking-in desk.
Generally, handcuffs were removed early in the booking-in process once the CSO was satisfied that they were no longer necessary. On one occasion the researcher observed that they were not removed for about 14 min, but the CSO then explained to the detainee that hand swabs needed to be taken which was why they had been left on. As shown in Fig. 3, there were more interactions involving use of force at Norfolk than at Cambs North or Cambs South.
A Mann-Whitney U test was conducted to compare use of force and each of the four elements of procedural justice given that there were only 30 instances where use of force was noted. There was no statistical significance between any of the elements of procedural justice and the use of force.

Discussion
A number of interesting findings emerged from the data. First, the overall level of procedural justice by custody officers towards detainees did not vary across the three custody suites. However, a different picture emerged when procedural justice was split into its four main components of voice, trustworthy motives, neutrality, and respect. Custody officers at all three suites showed high levels of neutrality and respect in their interactions with detainees. This respectful treatment of citizens supports findings reported by Skinns and her colleagues (2014) who found that custody officers were polite and non-judgmental.
A more complex ture emerged for two elements of procedural justice: voice and trustworthy motives. There was evidence of variation across the custody suites in the opportunities they offered detainees to 'tell their side of the story'. This was especially true with CSOs at the custody suites with the lowest throughput of detainees than their counterparts at the suite with the highest throughput of detainees. However, the latter custody suite scored the highest for trustworthy motives. A possible explanation might be that the CSOs at this custody suite knew that they had to deal with each detainee as quickly as possible and that if they gave good explanations to them this would reduce the need for detainees to ask questions. These findings are consistent with those reported in studies of procedural justice in communities. For example, analyzing data from systematic social observations in Los Angeles, McCluskey and his colleagues reported that the lowest procedural justice score was for trustworthy motives (2019, p.224). Similarly, Nawaz and Tankebe (2018) reported that officers demonstrated low trustworthy motives during stop and searches. However, contrary to findings presented here, they reported high levels of voice. One reason might be that the processes involved in stop and searches require a citizen to account for things they may or may not have on them illegally. The reason trustworthy motives scored lower in custody suites may be because detainees are often repeat offenders who have been into custody before, with CSOs assuming that they know how things work and do not need to be given explanations. There is also pressure on CSOs to process detainees as quickly as possible to ensure that the officers who escort them into custody or subsequently process them can resume their other duties. This may account for voice being the lowest scoring element of procedural justice. The influence of the Police and Criminal Evidence (PACE) clock, which generally means officers only have 24 hours to deal with a detainee before they must be released or charged, also adds to this pressure. PACE Codes of Practice and the Authorised Policing Practice on custody dictate the way that custody should operate, with much of this reflected in the question sets used by CSOs when booking detainees into custody. This may account for the higher scores for neutrality and respect. The second major finding concerns an understudied issue in procedural justice research, namely, the possibility of temporal effects: that is, whether the time of day a police-citizen interaction occurs affects the level of procedural justice displayed. The only previous study to have examined the issue was Nawaz and Tankebe's (2014) tracking of procedural justice in police stop and search practices in Manchester, UK. They reported that the level of procedural justice was greater at night, including the explanations officers gave and their neutrality. The current study found that the time of day affected voice, neutrality, and respect but not trustworthy motives. This finding of the study has important policy implications, which are discussed below.
The third major finding relates to the effects of demographic characteristics and offence severity. Do the levels of procedural justice vary according to CSO and detainee personal characteristics? A key finding here was the negative association between officer experience as a police officer and experience in the role of CSO, and trustworthy motives: as officers gained more experience, the level of care and concern shown for the wellbeing of detainees declined. A possible explanation for this finding comes from the police subculture literature. It reports that police officers sometimes develop cynicism on the job, which affects the quality of their interactions with some sections of the community, especially offenders (see, Bowling et al., 2019 ).
Finally, the results of the study do indicate that detainees are more likely to cooperate with the police if the quality of treatment and decisions made by CSOs are fair, with a statistically significant correlation between compliance of a detainee and the elements of trustworthy motives and respect. The evidence from procedural justice literature suggests that treating people fairly engenders compliant behaviour (Sunshine and Tyler 3). However, in their study of police interactions with detainees at custody suites, Savigar-Shaw and colleagues (2022) found that this was not always the case. On the contrary, being treated procedurally justly "was also a 'gift' that flowed from existing compliance and cooperation. In other words, fairness was offered by a powerful group to those who demonstrated subordination" (p. 788). There was an element of this in the observations we made.

Policy Implications
The findings reported show custody officers deliver high levels of respect and neutrality regardless of the custody suite they work in and with whom they interact but that the levels of these two elements were affected by the time of day. As the day wore on, the level of respect showed to detainees decreased. This could be because detainees were more likely to be under the influence of drink or drugs and less compliant at night, or that CSOs were tired from working shifts and less tolerant. If the latter, policy makers should review the shift pattern worked in custody. The improvement in neutrality as the day wore on might be linked to the reduced throughput, meaning that CSOs tended to give detainees more opportunity to have their say and are therefore seen as more impartial.
There is need to improve the delivery on two dimensions of procedural justice: the opportunities to hear the voice of detainees and the care shown for the wellbeing of detainees. Most people who go into custody are vulnerable and even if they have been arrested previously, offering them an opportunity to be heard is an essential part of the quality of their experience. There is a clear need for procedural justice training for custody officers that focuses on improving trustworthy motives and giving detainees a voice. The latter will involve going beyond, but not jettisoning, risk assessment questions which are vital to ensuring that detainees can be properly cared for whilst in police custody. CSOs should also be encouraged to ask all detainees if they have any questions about any aspects of the process.
There is also a need for targeted procedural justice training for more experienced officers and to provide them with a checklist to act as reminders of good practice. As the evidence showed, these officers displayed less procedural justice towards detainees. One possibility here is to create a procedural justice tracking standard for systematic random auditing of interactions. This will aid continuous monitoring and identification of at-risk officers. There is also the possibility of mixing the gender of officers on each team.

Limitations and Future Research
The study was not without limitations. First, although the sample of 150 was randomly generated, the sampling frame covered three months of custody recordings. This limits the scope for generalising the findings to the much larger population of CSO-detainee interactions in the year 2020 when there were over 9500 arrests.
Future studies that sample from the entire population of arrests over 12 months will help address the possibility of seasonal variations in the quality of interactions.
Secondly, the CCTV recordings analysed represented one phase in the detainees' interactions with officers. The study had no data on interactions before or after the booking-in process, especially how the former might have influenced the custody interactions. This could be addressed by tracking the experiences of detainees from the point of contact with officers through to the time they are taken into custody suites. These could involve analysis of recordings from police body-worn cameras.
Thirdly, officers do not always choose to be assigned to the custody role. Some do-but some are assigned to work in custody against their will. This raises an interesting question, with potentially important practical consequences: does the level of procedural justice delivered vary across these categories of officers? Future studies could address this question.
Fourthly, the effect on the level of procedural justice displayed of a detainee being intoxicated or suffering from poor mental health was not assessed and could be included in future research.
Notwithstanding these limitations, findings from this study have important practical implications. They raise the possibility for tracking procedural justice standards shown by CSOs to detainees not only in the police areas covered but nationally. This could form part of the auditing processes carried out by police custody inspectors and be used as evidence of good practice during HMICFRS/ HMIP inspections of police custody.