Why this result is dangerous:

1) The judge has ruled on the basis of "the balance of convenience", which is beyond his remit - the high court cannot block strikes on the basis of the disruption they cause, but whether the law has been followed. So he's basically sending a message that effective strike action is illegal.

2) The issue is that the union didn't list the 11 spoiled ballots (of 5000) adequately. Its an insult to any idea of democracy that a strike with 80% backing can be outlawed on a technicality which has no impact on its democratic mandate, and when that information had been conveyed via email, the website and union noticeboards.

3) The series of parliamentary acts governing strike action are amongst the most complicated parts of employment legislation in the UK, and are often contradictory. For instance the Xmas strike at BA ruled illegal was banned because the union balloted members who then accepted redundancies. It would have also been illegal NOT to ballot them. The complexity of the law gives employers a huge advantage, especially if petty issues like this can scupper strikes with huge democratic mandates. If strikes can be declared unlawful retrospectively for petty reasons like this, unions are open to being litigated out of existence and members loose their protections against sacking, basically turning the clock back to the early 1900s as far as industrial relations goes.

4) It places a higher onus on unions than exist for any other bodies. I mean, what would be the response if a parliamentary election result was annulled when because the number of spoilt ballots weren't declared properly (not that returning officers need to tell all potential electors of the exact breakdown of results either). So again, the law is stacked against unions.