Only for matters considered critical and sensitive for member states - finance, EU membership, harmonisation of legislation etc. it's mostly a hold over from th

Only for matters considered critical and sensitive for member states - finance, EU membership, harmonisation of legislation etc. it's mostly a hold over from the days of an EEC with 6 or 9 members (ie, right back when UK and Ireland joined in 73), when unanimity worked much better than it can now. Obviously to step back from unanimity requires unanimous vote without use of veto. :) Most matters are done under qualified majority - which is a small super-majority based on population. A post-Brexit UK going full on offshore tax haven might encourage the EU to get their act together on finance, and come up with some ways to crack down. Well, one can hope...