of the constitutional Roman republic.
http://en.wikipedia.org/wiki/Constitution_of_the_Roman_Republic
The Roman Republic had one of the earliest known constitutions. The idea for a constitution was likely copied from those of the early Greek city-states. Before the 17th and 18th centuries, the Roman Republic was one of the very few nations to have had a constitution. Many nations today have modeled their constitutions after that of the Roman Republic. Concepts that originated in the Roman constitution live on in constitutions to this day. Examples include checks and balances, the separation of powers, vetoes, filibusters, quorum requirements, term limits, and regularly scheduled elections. Even some lesser used modern constitutional concepts, such as the block voting found in the electoral college of the United States, originate off of ideas found in the Roman constitution.
The constitution of the Roman Republic wasn't formal or even official. Its constitution was largely unwritten, and was constantly evolving throughout the life of the republic. Throughout the 1st century BC, the power and legitimacy of the Roman constitution was progressively erroding. Even Roman constitutionalists, such as the senator Cicero, lost a willingness to remain faithful to it towards the end of the republic. When the Roman Republic ultimately fell in 27 BC, what was left of the Roman constitution died with the republic. The first Roman Emperor, Augustus, attempted to manufacture the appearance of a constitution that still governed the empire. The belief in a surviving constitution lasted well into the life of the Roman Empire.
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