Royal Mail's bid to stop strikes by postal workers in the run-up to Christmas will be heard by the High Court on Tuesday.
The postal company wants the potential strikes to be stopped due to alleged ballot "irregularities".
Royal Mail is taking legal action against the communication Workers Union (CWU) over planned walkouts.
Strike action was overwhelmingly supported by CWU members amid a dispute between workers and management over job security and employment terms.
The CWU said the result of the ballot – with 97 per cent supporting action on a turnout of almost 75 per cent – represents the largest vote for industrial action in several years.
But Royal Mail claimed the ballot was unlawful, pointing to evidence it said “demonstrates that CWU officials, including co-ordination and direction at a senior level, have planned and orchestrated breaches of their legal obligations”.
At a hearing in London on Tuesday, Mr Justice Swift will be asked to grant Royal Mail an injunction to prevent CWU members from taking industrial action.
Announcing the legal challenge in a statement released last week, Royal Mail said: “The company is making this High Court application because the integrity and legal soundness of any electoral process is vital.
Proportion of CWU members who backed industrial action, with a turnout of almost 75%
“This is particularly the case in relation to potential industrial action around the General Election on December 12 2019.
“Royal Mail is also making this application because of the damage industrial action would do to the company and its customers in the run-up to Christmas.”
The company added it found “at least 72” UK sites where staff were being instructed to vote Yes and asked to intercept and remove their ballot papers from mail coming into their delivery offices before they were delivered to their homes.
The chief executive and his board will go to any lengths to deny the democratic mandate of our members to stand together and fight for their future and the very future of UK postal services
The CWU previously said the result of the ballot, which was open between September 24 and October 15, represents the largest Yes vote for national industrial action since the passing of the Trade Union Act 2016.
A CWU spokesman last week told the PA news agency Royal Mail’s legal bid was “a desperate and sinister move”.
CWU general secretary Dave Ward added: “It will be clear to all our members and everybody connected with Royal Mail and this dispute that the chief executive and his board will go to any lengths to deny the democratic mandate of our members to stand together and fight for their future and the very future of UK postal services.
“Instead the company are pressing on regardless with their asset stripping plans to set up a separate parcels business and let thousands upon thousands of jobs wither on the vine.”
The hearing is due to start at 2pm.