“Article 50 of the EU Treaties gives the legal framework for withdrawal. And the EU Treaties provide for a 2-year process of withdrawal once Article 50 is activated. But several uncertainties still apply and these are likely to be exacerbated by political upheaval.”
“Article 50 sets no timeframe for when the PM needs to notify the European Council of the planned withdrawal — at which point Article 50 would be activated. This is important because (a) notification determines when the 2-year window on withdrawal starts and (b) parts of the Leave campaign wishing to retain access to the Single Market may want to use this procedural uncertainty to extract further concessions from the rest of Europe.
“In our view, the rest of the EU is unlikely to allow the UK to extract concessions from a further renegotiation by exploiting these uncertainties. The domestic political fallout in the UK is likely to be significant. The strength, composition and leadership of the government are likely to be uncertain, at least initially. Such political uncertainties may further complicate how a definitive referendum outcome is translated into a formal procedure.”
The referendum itself was advisory, rather than legally binding. Prime Minister Cameron had indicated before the referendum that he would respond to a Leave decision by beginning the legal process of withdrawal.