Both injunctions were granted on the grounds that the notices given by the unions were defective and the explanations given to describe the steps the unions had taken were inadequate.

In discharging the injunctions the appeal Judges held for the first time that the international recognition and context of the right to strike is relevant to the interpretation of the United Kingdom legislation.

In ASLEF v London Midland, the court found that the union believed it was balloting the relevant drivers and no one else but, because of human errors and failings, it did not achieve that objective and accidentally extended the vote to two members not entitled to it. The Court of Appeal considered this to be a case where the small accidental failures provisions of the Trade Union and Labour Relations (Consolidation) Act 1992 should have applied.

The CA also concluded that the explanation ASLEF had given on the ballot and strike notices “although brief, was sufficient to satisfy the statute and the [High Court] judge misdirected himself as to the specificity required.”

In the same way, the RMT’s explanation given in its ballot and notices for strike action at SERCO Docklands was adequate, the CA said. The court accepted that the approach adopted by the union in notifying the employer of the jobs identified by the workers themselves was perfectly sensible and complied with the statutory obligation.

Thompsons head of employment rights Victoria Phillips said: “This is an important decision which goes against the trend where the ability of trade unions to take collective action has been ruled out by the courts due to small mistakes in the balloting process, therefore undermining the fundamental human rights of trade unions and their members.”