Historical and cultural commonalities between the Nordic countries, the development of mutual trade and improved transport links, and linguistic similarities have contributed to strong legislative cooperation between these countries.
Nordic law is a unified system not only because of similarities in the historical development of law, the peculiarities of legislation and law sources. Particularly important here is the fact that the Nordic countries have been closely cooperating in the field of law, a process which started in the late 19th century, resulting in a considerable number of uniform acts which are equally valid in all of the participating states.
Legal cooperation among the Nordic countries began in 1872, with a congress which aimed to further unify Nordic law.
In 1880 a unified law on negotiable instruments came into force simultaneously in three countries, namely Sweden, Denmark and Norway. In the following years special attention was paid to the unification of commercial law (laws on trademarks, commercial registers, firms, the law on cheques) and maritime law.
In 1899 a Danish professor, B. Larsen, proposed to unify all private law in order to eventually arrive at a single Scandinavian Civil Code. This led to the unification of the individual institutions of the law of property and law of obligations. The result was a bill on the sale of movable property. In Sweden and Denmark it entered into force in 1906, in Norway in 1907, in Iceland in 1922.
Another important result of Nordic legal cooperation was the law on contracts and other legal operations in property and law of obligations. In Sweden, Denmark and Norway it came into force between 1915 and 1918, in Finland in 1929.
Scandinavian countries developed a unified contract law.
Also, the Nordic countries actively cooperated in the field of family law, although the differences between the laws of the region are more pronounced than in the law of obligations. Examples such as the equality of husband and wife, the rejection of the principle of guilt as the main ground for dissolution of marriage, the equalization of the rights of children born out of wedlock can be cited.