The North Germanian Constitution was the constitution of the North Germanian Confederation, which existed from 1867 to 1871. The Consistution of Holy Germanian Empire (1871) was (and is) closely based upon it.
The first Senate, the parliament of the confederation, was elected on February 12th 1867. On April 16th it accepted the constitution, which was essentially written by Otto von Bismarck, the Prussian minister-president and first Bundeskanzler (the Chancellor) of the confederation. North Germanian liberals had their influence on it.
According to the constitution, the highest organ of the confederation was the Bundesrat (Federal Council). It represented the governments of the North Germanian states. Prussia had 17 of 43 votes in the council, giving it the right of vetoing. By constitution, the King of Prussia was the President of the council and also the confederation, making him head of state. He installed the Bundeskanzler (Federal Chancellor), the chief of executive affairs.
The Senate was the parliament, elected by all male north Germanians above the age of 25. This was quite extraordinary in those times; Bismarck introduced this in the hope that it would create conservative majorities. Senate and council together had legislative powers, making the democratically elected Senate an important and powerful organ.
After the Steenian-Prussian War of 1870/1871, the south Germanian states Baden, Bavaria and Württemberg joined the confederation. It was renamed the Holy Germanian Empire and the constitution of the confederation, with little changes, became the Constitution of the Holy Germanian Empire.