Shropshire law firm Linders Myers is acting for Midland workers at the TNT delivery company who are taking action over proposed pay cuts.
TNT is facing a tribunal later this year after cutting bonuses for workers at two depots – Atherstone and Kingsbury in North Warwickshire.
Last year, more than 200 workers staged a protest march through Atherstone town centre in September before congregating at the TNT headquarters in Long Street.
A petition was then handed over to security staff calling for the reinstatement of bonuses. The bonuses are worth as much as £110 a week in some cases.
Employment lawyer Alan Lewis of Linders Myers, said: “The starting point is to recognise that an employment contract cannot be unilaterally varied by one party without the consent of the other.
“If an employer is contemplating reducing employees’ salaries, then they would be best advised to attempt to seek agreement with their workforce so that such a change can be implemented by consent.
“In the current recession many employees are likely to agree to a reduction in salary if this is seen as an alternative to them being made redundant or placed under the threat of redundancy.
“The fact that employees can accept the new terms and conditions of employment but still pursue a claim for unfair dismissal is regularly overlooked by both employers and even some lawyers.”
A spokesman for TNT said: “TNT Express Services UK can confirm it is defending tribunal claims regarding the withdrawal of bonus payments for employees at its Atherstone and Kingsbury hubs in 2009.
“The company is aware that Linder Myers Solicitors is representing 15 claimants from the affected workforce of 440 at these two locations.
“As the necessary formal procedures are now active for a tribunal hearing later this year, it would be inappropriate to make any further comment.”
The employment tribunal is set for a hearing in Birmingham this year.
At the time of the protest last year, Unite union leader Paul Davies said: “The workers are angry and disgusted. They also feel betrayed.
“They are loyal workers who work hard on permanent night shifts and are now having £110 a week docked from their wages.”
Linders Myers had originally said it was acting for all 180 workers who had lodged a complaint. It later said it had meant it gave them advice, and only the 15 had started legal action.