The Mierscheid-Law is an empirical law, published July 14, 1983 in the German Vorwärts magazine by Jakob Maria Mierscheid, predicts the vote of the Social Democratic Party of Germany (SPD) based on the size of crude steel production in western Germany. July 14 is the 195th day (196th in leap years) of the year in the Gregorian Calendar, with 170 days remaining. ... 1983 is a common year starting on Saturday of the Gregorian calendar. ... Jakob Maria Mierscheid (born March 1, 1933) has been a fictitious politician in the German Bundestag since December 11th, 1979. ... The Social Democratic Party of Germany (SPD – Sozialdemokratische Partei Deutschlands) is the oldest political party of Germany still in existence and also one of the oldest and largest in the world, celebrating its 140th anniversary in 2003. ...

The Vote share of the SPD equals the Index of the crude steel production in the western federal states - measured in million tons - in the year of the federal election.

The last proof of the law was in the 2002 election, where the West German crude steel production was 38.6 million tons, and the vote share of the SPD 38.5 %.