The case was brought by technicians employed by Tyco in Spain. Their duties are to install and maintain security systems at customer sites within a specified territory.

Previously, the technicians would report each morning to a branch office to pick up a job list and their van. Their working time was calculated as starting when they arrived at the branch office and ending when they returned to the office to drop off the van at the end of the working day.

When Tyco closed the branch offices, the technicians were nominally assigned to a central office in Madrid, but in reality they had no fixed or regular place of work. Instead they were given a van and would travel directly from home each day to the relevant customer sites, which could be up to 100km away, and return directly home from their last assignment. Tyco now calculated their working time as beginning when they arrived at their first assignment and ending when they left their last job of the day.

Tyco's new approach to calculating working time therefore discounted significant travelling time at the start and end of each day. The technicians claimed that this time should count as working time and that their working patterns were in breach of Spanish laws implementing the Directive.

Both the Advocate General and the ECJ agreed that the technicians' journey time to and from home each day was time when they were working at their employer's disposal and carrying out their activities or duties and so met the definition of "working time" under the Directive (www.practicallaw.com/2-617-5078).

The decision therefore establishes that for workers who have no fixed place of work, and carry out their duties at customer locations, all journeys to and from the customer sites have to be classed as working time. The fact that the first and last journeys started from, and ended at, home was irrelevant. However, travel to and from home to the employer's own site or base at the start or end of the working day would not count.

As the WTR contain the same definition of working time as the Directive, tribunals and courts in the UK must now interpret the WTR in line with the ECJ's approach in Tyco.

For employers of mobile or field workers, the key issue raised by Tyco is whether they have to change their existing working patterns in order to comply with the restrictions on working time under the WTR.

The first key restriction under the WTR is the average weekly working time limit of 48 hours per week, typically calculated over a reference period of 17 weeks. Unless the worker has opted out of this limit, employers have an obligation to take reasonable steps to ensure that this limit is observed and to keep and maintain records to show compliance with the limit over the previous two years. Breach of these obligations is a criminal offence. Case law under the WTR also establishes that workers who have not opted out have a contractual right to cease working if continuing to work would exceed the maximum hours permitted in any reference period.

Without an opt out, the mobile worker's employer faces a number of challenges. Assignments have to be allocated so that the average weekly working time limits are not exceeded when travel time to and from home is factored in. The worker needs to keep accurate records of start and finish times each day to enable compliance with the record keeping obligation and to allow the employer to keep track of how much working time is left in the reference period. Delays caused by significant travel disruption introduce another variable to be taken into account. Work scheduling and allocation could become more difficult.

Opt-out agreements are the key method of avoiding these problems. They also remove the obligation to keep records of daily working time. However, workers do have the right to refuse to opt out or to opt back in on at least three months' notice. Without the opt out, the employer would have to explore whether other flexibilities under the WTR would allow average weekly working time to be calculated over a longer period than 17 weeks, in order to provide greater flexibility in work scheduling.

Another key provision of the WTR is the entitlement to a daily rest period of 11 hours. In theory, this means that a mobile worker returning home at 8 pm could not be required to set off the next day before 7 am. However, this is an entitlement which workers can waive and employers do not have a strict obligation to enforce these rest periods. There is also scope under the WTR to require work on an ad hoc basis during a rest period as long as compensatory rest is offered later or to modify the entitlement to rest periods through a collective or workforce agreement on a more permanent basis.

Importantly, this decision does not automatically mean that mobile workers are entitled to be paid for time spent travelling between home and customer sites. The WTR do not require working time to be paid. Pay is an entirely separate issue governed by the national minimum wage legislation and the contract of employment.

Under the National Minimum Wage Act 1998 and the WTR, the general position is that travel time between home and a place of work, including for mobile workers, is excluded from the obligation to pay the national minimum wage. That is also backed up by case law. In Whittlestone v BJP Home Support, the Employment Appeal Tribunal held that the minimum wage applies to the time spent by a care worker travelling from one client to another, but not to the time she spent travelling between clients and home (UKEAT/0128/13/1907).

The only other route to payment would be under the employment contract. If this travelling time is currently unpaid, it is unlikely that this decision will create any new right to be paid. However, ambiguous wording in a contract, especially where workers are paid on an hourly rate basis, could be exploited to create a basis of payment or to argue that travel time uses up normal hours of work, triggering overtime rates during what are currently treated as standard working hours.

Workers and unions may pursue the issue of unpaid travelling time in other ways, for example by giving notice on opt-out agreements or taking a restrictive interpretation of the employment contract in relation to working hours and start and finish times to strike a balance between maintaining normal working patterns against payment for travel time. Employers will need to be alive to these risks.