The upcoming withdrawal of the United Kingdom from the European Union is a source of tensions within the political system of the UK. Devolution is most likely to be affected by Brexit which can lead to conflicts between the UK as a whole and Scotland as its part. The Sewel Convention is a political constitutional norm establishing non-legal rules of cooperation between these two political bodies. Despite having been written in a statute, the Sewel Convention remains unenforceable by the courts. Nonetheless, the political consequences of diminishing it may be severe. The discrepancy between the political strength of Scottish nationalism, confirmed in the latest general election, and constitutional lack of Scottish “voice” in regard to Brexit may lead to a severe political crisis within the UK.