I think you're misunderstanding what I stated, I didn't doubt that there was a law, but it is a fact that the ECJ don't make law, they interpret it.
In this case the law relates to the labelling and marketing of foodstuffs and whether they are food or medicine and labelled as such.
This ECJ decision which is an interpretation of the law relating to the labelling of foodstuffs was made in 2005! so it's not recent as you stated and presumably to date has not caused problems for Irish Exporters, however my point still stands contact Bord Bia for advice.
If you want to look at the ECJ decision see here
[broken link removed]
The decision states that any foodstuffs before the 1997 regulation discussed are kosher, so that if fluoride was in use in ireland before then i would interpret that as being okay.