Secret ballot
From Conservapedia
The secret ballot, also known as the Australian ballot, is a major feature of the United States voting system. A secret ballot is unable to be inspected by anyone else after it has been cast (with the obvious exception of poll employees during recounts). While the secret ballot is mandated by the U.S. Constitution, some experts consider it a poor choice. In particular, the lack of accountability attached to a secret ballot means that voters in an election may not feel the same level of personal responsibility as voters in a more open society. The beneficial peer pressure attached to an open ballot, in contrast, helps to ensure that a few antisocial voters do not overturn community standards.