[mattmanser]

The Irish firm has 'mac' in their name.

Supermac’s said it can now expand in the United Kingdom and Europe. It said it had never had a product called “Big Mac” but that McDonald’s had used the similarity of the two names to block the Irish chain’s expansion.

https://www.reuters.com/article/us-mcdonald-s-corp-trademark...

From the other articles I've seen about this the implication is that the judgement was probably heavily influenced by McDonald's own anti-competitive shenanigans of trademarking names of competitors products:

The US chain had also trademarked the term “SnackBox,” an offering by Supermac's that McDonald’s does not offer.

https://www.irishcentral.com/culture/food-drink/supermacs-mc...

[philliphaydon]

Ah I initially got confused because I thought supermac was some bigger Big Mac I had not heard of and went to Google. Disappointed now.