A basic understanding of the process and systems should calm the nerves of the detained citizen-driver will calm those fears. Citizens should know and understand that the police have limited powers and simply perform carefully limited services following rules and procedures with safeguards and a chain-of-command with overseers, dispatchers, supervisors and review boards. Police serve in the executive branch of government, the courts serve in the judicial branch of government, and both follow and enforce laws written by the legislative branch of government. The federal and state governments consist of a legislative, executive and judicial branches of government.  This is historically based to divide up the power of government in to these three separate-but-equal parts of government. So police must convince a judge that an offense has been committed and ask the court to impose a punishment within the parameters of the written law (laws written by the legislative branch of government).