The Rail Maritime and Transport union says it will fight the legal action brought against it by East Midlands Trains.
The rail company is taking the union to court after members stopped doing overtime.
RMT are determined to defend the union's position on this matter.
Our demands are not unreasonable and we firmly believe that management should sit down and enter into meaningful negotiation with RMT, instead of hiding behind the anti-trade union laws in an attempt to prevent the union from taking industrial action.
East Midlands Trains is taking the Rail Maritime and Transport union to court after members were banned from doing overtime with the company.
The union said there had been a dispute over a number of issues, including the scheduling of work.
We have been forced to start legal proceedings to prevent the RMT from trying to cause disruption to our passengers by encouraging and misleading our employees into taking unlawful strike action.
This is an invented dispute and there is no substance to the allegations made by the union.
East Midlands Trains is taking legal action against a trade union, after members stopped doing overtime at the company.
Members of the Rail Maritime and Transport union banned overtime at the rail company, which caused disruptions to rail services, including cancellations and delays.
East Midlands Trains says the strikes are illegal, but the RMT union will challenge them in court.
Neil Micklethwaite, East Midlands Trains Customer Service and Commercial Director, has told ITV News Central Nottingham Station will stay open during the £100 million signalling upgrade.
A £100m rail upgrade across Nottinghamshire will cause disruption across the East Midlands this summer - to find out how click here.Read the full story ›
Speaking about today's timetable changes during the signalling upgrade work this summer, the Managing Director of East Midlands Trains said:
"Every effort has been made to deliver the best possible service forour passengers during Network Rail's re-signalling works whilstrecognising that some people will face considerable changes to their normal journey.
"We have invested around three years of careful planning to ensure we can keep people on the move throughout the work at Nottingham.
"Our advice for passengers is to be prepared and check in advance of travel at [eastmidlandstrains.co.uk/
Commuters in Nottingham will find out how much they'll be affected by a £100 million project to upgrade railway signals in the county.
Major disruption is expected throughout July and August when the redevelopment work is taking place.
New timetables are being published today which explain which services will have to change during the construction work, with some trains being cancelled altogether.
Thousands of passengers travelling on East Midlands Trains are likely to face severe delays until the end of the week because of extensive damage to overhead power cables.
A one kilometre section of overhead line is down at Radlett in Hertfordshire.
Delays to and from London could be up to an hour.
For more information see the East Midlands Trains website.
Services on East Midlands Trains to and from London St Pancras are now expected to run as normal.
Lines between Leicester and Loughborough are also expected to be re-opened following overnight closures.
Network Rail had to carry out emergency repair works following the derailment of a freight train at Barrow on Soar (between Leicester and Loughborough) on 27th December.
Train services will be unable to call at Barrow Upon Soar until later notice because further remedial work is required following the derailment of a train carrying over 1,000 tonnes of stone.
I apologise to all those who have been inconvenienced by this work and thank passengers for their continued patience. Removing the wagons safely is a complex job and this location is not easily accessible, all of which has added to the time it has taken to complete.
Rail fares on East Midlands Trains will increase by an average of 4% from the 2nd January 2013.
A single journey will rise by an average of 52p.
Railway funding can only come from the taxpayer or from the passenger. The government's policy remains that a bigger share must come from people who use the train.
Passangers can check the new price of their usual ticket or any other fare on the East Midlands Trains website.