The Holy
Roman Empire, despite its name, was not a unitary state, but a
defensive confederation of states, most hereditary monarchies, but
some elected aristocracies, and the head position of "emperor" was
elected, serving for life, but not hereditary, with limited powers.
He ruled from Rome. But there was no requirement that he be a
subject or resident of the Empire, only that he be one of the
hereditary nobility of Europe. During its height, it extended over
much of north-central continental Europe, from Belgium to the border
of Poland, and across the northern half of Italy, with hegemony over
other nearby countries. The princes that could cast votes for
emperor were called "electors". Its borders and extent changed often
from 962 through 1806, but during that period it retained roughly
the same "constitution", expressed not in a single written document,
but in a large number of separate treaties and charters.
It is sometimes said that the Framers of the U.S. Constitution had
no model for an extended federal union or republic, but that is not
quite correct. Many of their design ideas, and some of their terms,
came from the example of the Holy Roman Empire. It is from it that
the choice was made to call the members "states", from the German stadt,
and to adopt the Electoral College, consisting of "electors" as the
method of electing the President.
The following links are to documents that tell more of the story:
The
Holy Roman Empire — General discussion
Constitutions of Frankfurt 1220 — Recognising the rights of spiritual and temporal princes.
Original Latin
Partial German translation
Constitutions of Frankfurt 1232 — Further recognising the rights of spiritual and temporal princes.
Original Latin
Partial German translation
Constitution of 1338 (Frankfurt) freeing the election of the emperor from papal control.
The Golden Bull of the Emperor Charles IV 1356 A.D. — Defines role of the electors.
Original Latin
English translation
Partial German translation
Edict of pacification (Ewiger Landfriede) of 1495, on criminal justice.
Partial German translation
Ordinances (Ordnungen) of 1495 (revised 1555) and 1518 (revised 1654) on the courts of justice.
Capitulatio Caesarea (Wahlkapitulation), issued at each election from 1519, consolidated in a perpetual edict in 1711.
Religious treaties (Passau 1552, Augsburg 1555) on religious toleration.
Concordats with the Holy See: Worms 1122, amended Vienna 1448.
Original Latin
German translation
Main resolution of the imperial delegation (Reichsdeputationshauptschluß) of 1803.
(German)
Treaty
of Westphalia (1648) (English)
Samuel Pufendorf, The Constitution of the German Empire (1667) (English)
The
Holy Roman Empire — General discussion
Samuel Pufendorf, The Constitution of the German Empire (1667) (English)