Held: the Government is not entitled to give notice of a decision to leave the EU under Article 50 by exercise of the prerogative powers of the Crown and without reference to Parliament. The Court ruled that nothing in the European Communities Act 1972 supports this power of the Crown. The Court considered the sovereignty of Parliament to be critical, and stated the Crown was not entitled to change domestic law through exercise of its prerogative powers.
Helen Mountfield QC, Jessica Simor QC and Rhodri Thompson QC were involved in this case.
Judiciary.gov.uk (Judgment and Press Summary)https://www.judiciary.gov.uk/judgments/r-miller-v-secretary-of-state-for-exiting-the-european-union/