Further common ground appered at paras 24 to 29 where the court set out basic principles relating to prerogative power and also at paras.37 to 40 where there is a basic picture of how EU law operates.
The giving of notice would have no immediate impact on domestic law because the European Communities Act 1972 (ECA72) would remain in place and so would EU rights. That view overlooks the effect that the notice will eventually have particularly if it is truly the case that notice cannot be either conditional or revocable (as was assumed by all parties to the case).
As the court noted (para 11) - Once a notice is given, it will inevitably result in the complete withdrawal of the United Kingdom from membership of the European Union ..... and it will also be the case that a withdrawal agreement may preserve some parts of the relevant Treaties or may make completely new provision for various matters. That would give the Crown entitlement to pick and choose which existing EU rights, if any, to preserve (so long as it can persuade the European Council to agree) and which to remove. This is why the court saw the effect of the Article 50 negotiation process on relevant rights as direct.
The court decided that nothing really turned on this because it was clear that the two provisions have to be read together and if the Crown did not have power to give a notice under Art 50(2) then it would appear that it could not make a decision to withdraw under Art 50(1). The court agreed with Lord Pannick QC that whatever the position in relation to any decision under Article 50(1), a decision to give notice under Article 50(2) was the appropriate target for the legal challenge because it is the giving of notice which triggers the effects under Article 50(2) and (3) leading to the exit of a Member State from the European Union and from the relevant Treaties.