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:Henry Sumner Maine's Ancient Law: Mr. Maine wrote many important works and this is one of them.
Frederic Bastiat's The Law: If you have not read this book, you should.
John Stuart Mill's Essay on Liberty: This work should be read by the serious student of liberty.
II. America From the Revolution and After:
Thomas Paine's Common Sense: Paine was one of the major motivator's of the Revolution.
Collection of Historical Works from the Library of Congress: This site contains a huge collection of historical works.
The Making of America by the University of Michigan's Library: This site also contains a very large collection of important books.
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.
The Avalon Project:
Yale Law School has engaged in an effort to collect and post
numerous works regarding the founding of this country.
also has some historical works posted on its site.