What did the court say?
Until now, those employing mobile workers who had to travel to get to or from their first or last appointment of the day were not required to count that time as work.
On Thursday, the European Court of Justice judgement ruled those without a fixed or habitual office should consider the time they spend travelling between their homes and the premises of their first and last jobs as part of their hours for the day.
The ruling relates to the Working Time Directive - the European initiative which caps the working week at 48 hours. In the UK, employees have the option of opting out of the directive.
I'm a care worker who travels to different patients' homes. Am I affected?
Possibly, yes.
Employees who fall into the category loosely defined as "mobile workers" - those who habitually travel to different places of work - could be affected.
Simon Bond, an employment specialist at Higgs and Sons solicitors, says the most obvious group to fall under this definition is carers not already paid for travelling to their first and last jobs. Sales people who travel between sites and employee workmen and women, such as plumbers or electricians, could also fall into this category.
As many as 975,000 people in the UK could fall under the remit of the ruling, says Paul Sellers, a policy officer at the TUC.
And some employees could be working an extra 10 hours a week once travelling time is counted, Chris Tutton, an employment lawyer at Irwin Mitchell, adds.
I travel a lot for work, but I have a permanent office
The ruling is less likely to affect people who work both in an office and remotely. If your contract includes a permanent base, you are unlikely to be able to successfully argue you are a mobile worker, Mr Sellers says.
There may, however, be cases where it is possible to argue that a permanent base is meaningless because of the length of time spent outside the office.
I have to commute two hours every day to my office
For those with a permanent office (however lengthy your commute), this ruling will not have an effect. Mr Sellers says this final group is the "overwhelming majority" in the UK.
I think I'm affected. Should I expect a pay rise or a change in my hours?
The ruling could eventually affect pay. Unions say the ruling does not directly deal with remuneration, focussing instead on working hours and conditions. But it is possible the European judgement will be used in UK courts to challenge employers who pay an average hourly rate under the minimum wage (once travelling time is taken into account).
That could mean employers facing increased wage bills and raises an outside chance costs for some services, such as cleaners who have to travel and are paid a low wage, could go up.
It could also lead to a change in working patterns - especially for those who do not choose to opt out of the 48-hour maximum.
"I think some employers will look at where they're sending staff - they might try to make sure that the first and last shifts are as close to home as possible because they don't want to eat into that working time that they have," Mr Tutton said.
We have been contacted by BBC News website readers in response to the European judges' ruling.
Here is a selection of their comments:
This is great news for the likes of me and my engineers. We work in the telecoms industry visiting multiple sites daily. We don't get paid travel time but are expected to be onsite for 9am and leave the last site at 5pm wherever that may be. If the sites are two hours away from home this adds four hours to our day that we don't get paid for, so we do a 12-hour day for eight hours work. Steve Carroll, Manchester
I am a sales rep. My hours of work are 35, working nine to five. I leave my house most days at 6am as I work on the M25 strip so it takes three to four hours to get to my first appointment. I might get home at 7pm with no lunch break. I can drive for seven hours total per day, that's before my day working. I feel fed up, very tired and underpaid. I don't know what my rights are! Erica, Cambridge
I am a pest control technician. My colleagues and I sometimes end up doing 11 or 12-hour days. These lost hours travelling can take its toll on missed family time. The amount of time driving both during the working day and the travelling time to and from work can sometimes be as much as six hours a day depending on where our jobs take us. Paul Godfrey, Swindon
I currently leave for work - as a service engineer - earlier than my first job to ensure I'm at my first site by 10am. It's wrong that I should use my time as the further away it is the more my own time is used. We also do not have a structured break time and I've worked over 11 hours without a break and it's a constant driving service job. Barry Corbett, Glasgow
I am a mobile gas fitter and I am expected to travel to my first appointment and from my last appointment in my own time which can add 10 hours to my working week. Mark Hannon, Castleford
I'm a gas repair engineer. We have no offices. Our policy is to be on the patch of work or at our "pickup" point by 8am. With heavy traffic I leave home at 7.20am. This leaves me with 40 minutes of extra travel time. Also I could be working miles away from home at the end of day resulting in a huge variance of time out. Daniel Richards-Smith, Dorset
I am a homecare worker, taking care of people in their own home. I do not get paid for travelling to work or in between appointments. Sometimes I can travel up to 50 miles a day. We get paid 30p per hour of care delivered in a day. This is not petrol money as the carers who walk between calls also get paid this. Sometimes we have to sit in our cars because it is too early to go in to the client, anywhere from 10 minutes to up to and hour as we often are too far away from home to make it feasible to travel home. Susan Turnbull, Barnsley
I'm a healthcare assistant and while I agree with being paid for time it takes to travel I can also see this as having a knock on affect to the clients as the money to pay us would have to come from somewhere. Susan Bird, Kent
Time spent travelling to and from first and last jobs by workers who do not have a fixed office should be regarded as work, European judges have ruled.