This will again be short as this is a breaking story. The Supreme Court in the UK has voted 8-3 in agreement with the prior High Court decision that triggering Brexit can only happen by an act of Parliament.
Initial coverage from CNNis here and from the BBC here.
The Court also ruled that the government does not need the direct approval of Scotland, Wales, or Northern Ireland. Some implications of this are obvious, such as it may be hard now to stick to PM May’s intended schedule of triggering Brexit in March, and others will take some time to work out, such as whether Parliament now backs out.