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Standby or on-call: are your employees working or resting?

Working time includes any period where a worker is working, at their employer’s disposal and carrying out activities or duties. Time spent on-call may or may not satisfy this definition. 

In Thomas and others v The Chief Constable of Humberside, a tribunal had to decide if standby arrangements under which staff had to regularly respond to calls and were restricted in terms of what they could do when they weren't working, amounted to working time for the purposes of the Working Time Regulations 1998 (WTRs).


The claimants are employed by the Humberside Forces Covert Authorities Bureau and work as the single points of contact to determine the appropriateness of requests from the police to access data from telecommunications, social media and the web.  

Up until September 2023, the claimants had been working during standard business hours from Monday to Friday, starting at 07:00 and ending at 16:00. They were also on a standby rota which required them to be available for 12 hours outside their core hours during weekdays, and for 24 hours at the weekends and public holidays. During standby shifts, they answered calls and had to log onto their laptops to deal with queries. They received an on-call allowance and hourly rates when they were called out. 

The claimants regularly had to work when they were on call. On average, they worked almost one in two standby shifts for an average of between three and six hours and, sometimes for much longer. 

Their contracts of employment referred to a separate standby agreement which stipulated that they had to immediately respond to calls and to remain at home unless they needed to go out. It made it clear that staff that did not adhere to this could be disciplined. 

In 2022, discussions began between the trade union, Unison, and the respondent about on-call time and a shift pattern change to 24/7, which was eventually implemented in September 2023. 

There was some confusion about the new arrangements and, after staff threatened to take legal action, an employee issued guidance to clarify what staff could and couldn't do when they were on standby. It provided that:

  • staff had to remain contactable and be able to respond to the most serious incidents (where there was a threat to life) as soon as reasonably possible
  • in most cases a delay of up to 30 minutes to deal with the request would be reasonable
  • they could work from other locations if they could ensure their work remained private
  • they could go to a restaurant or go shopping

Unison said that these rules had not been agreed through collective bargaining and did not reflect the experience of the workers, or the expectations of the police. 

A group of employees took proceedings against their employer, arguing that their standby shifts amounted to working time and they should receive compensatory rest after working them.  

Tribunal’s decision

The tribunal said that the standby agreement included contractual terms that had evolved with technological and working practice changes and were binding on the parties. The guidance, by contrast, did not reflect the expectations of the contracting parties and had been issued as an interim solution pending the change to 24/7 work. 

The standby agreement severely restricted what the claimants could do: they had to stay at home, or very close to it, and generally had to schedule personal engagements and social events when they were not on standby. The tribunal accepted the evidence from one of the claimants that, because of the sensitive and confidential nature of the matters she was dealing with, she didn't attend family events, go to the cinema or take her daughter swimming when she was on-call. The tribunal also accepted that it was not realistic or practical for staff to go shopping, to the cinema or a restaurant given that the length of the average time they were required to work.

The tribunal recognised that some of the features of this standby arrangement apply to many types of on call activity and wouldn't amount to working time. But in this case, the combination of the need to respond immediately (which was in single minutes not up to 30 minutes), geographical restrictions, frequency and unpredictability of calls, and the need to remain mentally alert meant that the standby duty was working time.  


Generally, on call/standby time will be treated as working time for the purposes of the WTRs: 

  • when the worker carries out duties, such as attending call outs; and 
  • if the worker is required to remain at their workplace (even if they can sleep there) or some other place (which can include their home if it significantly restricts the worker's ability to pursue personal activities)  

If a worker is free to do as they wish, and at a place of their choice whilst on call, the time will not usually be treated as working time.  The employee will only be working for the purposes of the WTRs when they respond to a call. 

In this case, the employer significantly restricted what workers could do whilst they were on call because of the need to respond to calls and to start work immediately afterwards. In particular, they had to remain fully alert and that inhibited their ability to switch off and relax, or to fully engage into other activities. This tipped the balance in favour of treating all of the standby time as working time.

Workers who are working when they are on call are entitled to an uninterrupted rest break of at least 20 minutes if the working day is at least six hours long, and a daily rest period of at least 11 hours in each 24-hour period. In this context, a period of “down time” (when the worker is not undertaking any particular duties but is nonetheless working) cannot retrospectively become a rest break.  The worker must know at the start of it that it is a rest break which they can use as they please and is not time on call.  This can create challenges for employers who need to have staff performing duties which require a continuous presence.  

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