The Irish Congress of Trade Unions must feel a bit like Humphrey Bogart in Casablanca over its decision to stage a day of action on 30 March.

Bogart's "Of all the gin joints in all the towns in all the world, she walks into mine" could just as well read "Of all the days in all the year we had to choose that one" – one of the days on which the Leaving Certificate oral examinations will be held.

The state exams commission has decided to change the days of this element of the exams because of the risk of industrial action – nerves are too strung out among students to prevaricate over when these tests will take place or not.

But for the unions it is a self-inflicted injury. The aim of the industrial action was to demonstrate again the unfairness of the levy, public service cuts and the failure of employers to stick to their side of the partnership deal.

Perhaps ICTU was gambling the one-day strike could be called off if partnership talks with the government and employers resumed again. That looks less likely by the day now.

The teachers themselves never decided on 30 March as the date for the national protest – but the thoughtless choice of that date is definitely a case of how not to win friends and influence among more than 100,000 very stressed parents of equally stressed young people.