A 48-hour strike by London Underground maintenance workers will go ahead tonight after the High Court refused to grant an injunction preventing the stoppage.
Tube Lines had challenged the legality of the ballot carried out by the Rail Maritime and Transport union (RMT).
The walkout over pay, jobs and conditions is due to start at 7pm.
Mr Justice Tugendhat, sitting in London, said he had reached a "clear view" that he should not grant an injunction but gave no immediate reasons for his decision.
Bob Crow, general secretary of the Rail Maritime and Transport union, said: "This is a massive victory, not only for the RMT and our members, but for every group of workers who stand and fight against job cuts and attacks on working conditions.
"The strike goes ahead and will be solidly supported. We expect major disruption across the network."
Tube Lines's counsel, Charles Bear QC, challenged the accuracy of the RMT's ballot, claiming that the union had given information that 47 advanced train maintenance staff had voted, when only 30 were employed.
He told the judge: "The essential point you have to decide is whether the union has complied with its duty to provide information which satisfies the requirements of the statute."
Oliver Segal, for the union, said that the supposed inaccuracy was disputed.
In any case, he argued, Tube Lines's case was misconceived as the union's obligation was not to provide accurate information but information as accurate as was practicable in the light of the information in its possession at the time.
The matter will return to court on July 9 for a one-day hearing to fully consider the merits of whether to grant an injunction ahead of the next planned strike on July 14.Reuse content