In their search for personal liberty, Americans added the Bill of Rights to the Constitution shortly after its ratification. These amendments guarantee certain political, procedural and property rights against infringement by the national government. Freedom of expression is the most basic of democratic rights. People are not free unless they can freely express their views. Nevertheless, free expression may conflict with the nation's security needs during times of war and insurrection. The courts at times have allowed government to limit expression substantially for purposes of national security. In recent decades, however, the courts have protected a very wide range of free expression in the areas of speech, press, and religion.
The guarantees embodied in the Bill of Rights originally applied only to the national government. Under the principle of selective incorporation of these guarantees into the Fourteenth Amendment, the courts extended them to state governments, though the process was slow and uneven. In the 1920s and 1930s, First Amendment guarantees of freedom of expression were given protection from infringement by the states. The states, however, continued to have wide discretion in criminal proceedings until the early 1960s, when most of the fair-trial rights in the Bill of Rights were given federal protection.
"Due process of law" refers to legal protections that have been established to preserve individual rights. The most significant form of these protections consists of procedures or methods (for example, the right of an accused person to have an attorney present during police interrogation) designed to ensure that an individual's rights are upheld. A major controversy in this area is the breadth of the exclusionary rule, which bars the use in trials of illegally obtained evidence. The right of privacy, particularly as it applies to the abortion issue, is also a source of controversy.
Civil liberties are not absolute but must be balanced against other considerations (such as national security or public safety) and against one another when different rights come into conflict. The judicial branch of government, particularly the Supreme Court, has taken on much of the responsibility for protecting and interpreting individual rights. The Court's positions have changed with time and conditions, but the Court has generally been more protective of and sensitive to civil liberties than have elected officials or popular majorities.