Answer:
blood alcohol level
Explanation:
blood alcohol level test is used to test concentration of alcohol in human blood. Police administrate this test to check the legal limit of alcohol in human blood, means if alcohol in blood is higher than specific limit he or she is not allowed to drive as different mental and physical associate with different percentage of alcohol level in human brain.
As far as we know, those would be the Vikings: we know for sure that there was a Viking visiting Northern part of the continent in 11th century.
But we cannot exclude the possibility that there was something before too...