Edward Snowden is mistaken. He did not break the law because unconstitutional acts or policies are void ab initio.
Snowden needs immunity to testify against his superiors who engaged in criminal violations of the American people's constitutional rights.
The American people need not fear that opposing the government will lead to either anarchy or tyranny. We did this already and remember.
If you're an American fearing for our country it's time to re-read our founding document: http://www.archives.gov/exhibits/charters/declaration_transcript.html