The Magnus Erikssons landslag (Country Law of Magnus Eriksson) also called only Landslagen (Country Law) was a Swedish law passed by king Magnus IV of Sweden in circa 1350. It was the first attempt to a law applying to the entire nation of Sweden-Finland, replacing the previous local county laws of the Medieval Scandinavian law.
The Country Law applied to the entire countryside, but not to the cities, which were governed according to the Stadslagen (City Law), which were issued in about the same time, but was a separate law. The Law from 1350 were followed by the Kristofers landslag of 1442, but as they were used in parallel, it was not replaced by it.
It was in effect in Sweden-Finland until the Civil Code of 1734.
References
Magnus Erikssons landslag Wikipedia(Text) CC BY-SA