Who will watch the watchmen? Plato posed the question, but it is just as important today as it was 2,400 years ago. Power has to be kept in check, as the founders of our country knew when they designed a system of checks and balances in the United States Constitution. An agency that has the power to protect us from enemies also has the power to do us great harm. Police must be able to search for evidence if they are to catch terrorists or other criminals, but when police get access to information about us too easily they can abuse their power. It is vital to protect citizens from police intrusion. In the United States we do this by requiring the police to go to court and obtain a search warrant.