There are numerous documents that supply political and legal ideas. Many of these have had a profound effect on the modern world, even though the documents might have been written far in the past.
For instance, Hammurabi's Code was written in 1790 BC, but forms a vital precedent for modern laws. While some of the laws codified in this document are archaic and unscientific, their effect can be traced through to as late as the Middle Ages and even to today.
Another example can be found in the Ten Commandments. These commandments formed the backbone of Jewish law in the deep past, but the clear effect can be seen in the modern laws of the United States and other nations. Commandments such as "Thou shalt not kill" form the core of modern day laws.
Justinian's Code of Laws, or the Code of Justinian, came about in 529 AD, at the behest of Emperor Justinian I. This work had an enormous effect on law throughout the world, and even on canonical law in the Catholic Church.
Another important document is the Magna Carta, drawn up in 1215 in England. The Magna Carta gave explicit rights and protections to the populace, though these were largely limited to those considered free men, and not to serfs. Many of the regulations here later made their way into the nation's constitution and formed the backbone of constitutional law in much of the world.
In the same vein, the English Bill of Rights, which was written in 1689, gives additional rights and protections to those living under the rule of a constitutional monarchy. Many of these were actually derived directly from the great thinker John Locke, and served as a basis for the Bill of Rights in the US.
The US Declaration of Independence is another incredibly important document, which spells out numerous inalienable rights for individuals. This document, written in 1776, is technically only an explanation of why the thirteen American colonies succeeded from the British Empire, and does not actually include laws for the fledgling nation. However, its importance is unquestioned.
The US Bill of Rights is another incredibly important document, which owes much of its power to documents that went before, including the British Bill of Rights, the Magna Carta and others. The US Bill of Rights is the foundation for personal freedom in this country, and represents an enormous leap forward from its predecessors, though.
Of course, without the US Constitution, which puts limits on government, sets forth checks and balances, enumerates the powers of Congress and more, the US government would not be what it is today. This document amplifies and expands on concepts begun thousands of years ago, but with a new emphasis on individual rights and freedoms, as well as restrictions for government.
Finally, the Declaration of the Rights of Man and of the Citizen is a document put forth during the French Revolution, which defined the rights of individuals, as well as of the state. This document also influenced the various US laws and codes, as it set forth universal human rights that have been recognized as inalienable today.