The Net is a fantastic place to find important historical works regarding the law and government, and those which get posted grow daily. Here are some places which post such works and I highly recommend your visit to these sites for a study of the documents and books posted there:
I. Pre-Revolutionary:
1. Medieval Law: If you wish to learn more about very old law, visit this site.
2. Henry Sumner Maine's Ancient Law: Mr. Maine wrote many important works and this is one of them.
3. Frederic Bastiat's The Law: If you have not read this book, you should.
4. John Stuart Mill's Essay on Liberty: This work should be read by the serious student of liberty.
5. The American Colonist's Library: This page has lots of pre-revolutionary works, but probably more works leading up to and after the revolution.
II. America From the Revolution and After:
1. Thomas Paine's Common Sense: Paine was one of the major motivator's of the Revolution.
2. Collection of Historical Works from the Library of Congress: This site contains a huge collection of historical works.
3. The Making of America by the University of Michigan's Library: This site also contains a very large collection of important books.
4. Liberty Library of Constitutional Classics: Patriot Jon Roland has worked tirelessly to compile this enormous collection of important documents and books. You can get lost here.
5. The Avalon Project:
Yale Law School has engaged in an effort to collect and post numerous works
regarding the founding of this country.