This nation's basic charter, the federal Constitution, was ratified in 1789. Its most important amendments were attached just two years later. It is one of the most astonishingly prescient instruments ever drafted, providing a continuing context for the world's most complex form of government. Drawn up in the age of the horse and carriage and the single-sheet newspaper, the Constitution is serviceable nearly 200 years later in an era of moonwalks and television.

Lawyers try to explain the Constitution to courts and judges try to explain it to each other, but there have been few promising efforts to explain it to the vast majority of those to whom it applies. Now Fred W. Friendly, Edward R. Murrow Professor of Journalism at Columbia University, with an assist from Martha J.H. Elliott, has entered the lists.

Two warnings about the scope and purpose of Friendly's project must be issued at the outset. In the first place, his title over-promises. It is much too broad, since his book is not really about the primary document but instead addresses that collection of early constitutional amendments known as the Bill of Rights. And Friendly's book does not address all of those amendments. Its focus is on freedom of speech and press and certain individual rights.

The title refers to a delicate balance. Betweeen what and what? The authors seemed principally concerned with the balance between the powers of the federal government and those of the separate states until I encountered a chapter, tacked on at the very end, dealing with the balance of war-making powers between the president and the Congress, which has nothing to do with either the Bill of Rights or the federal-state relationship.

So far this may seem a quibble over a title. Rename this book "The Bill of Rights: That Delicate Balance" and delete the final chapter, and you have a reasonably accurate description of an essentially journalistic treatment of some crucial constitutional safeguards that regulate the federal government and, often but not invariably, the states.

What Friendly and Elliott have done is exemplify the workings of a few important constitutional protections by describing the landmark litigations, early and recent, in which the contours of those guarantees were picked out. The authors begin with a description of Marbury v. Madison, the case in which Chief Justice John Marshall established the supremacy of constitutional dictates over legislative enactments and the power of the Supreme Court to interpret those dictates.

In the same chapter, Friendly and Elliott sketch the controversy surrounding the adoption of the Bill of Rights (Jefferson and Madison believed fervently in a written catalogue of liberties, shielding the minority from "the tyranny of the majority"; Hamilton thought it superfluous, nothing more than a list of "aphorisms . . . which would sound much better in a treatise of ethics"). The first chapter ends with a reference to the Supreme Court's 1833 holding that the Bill of Rights applied only to the federal government, not to the states. It was not until well into the 20th century that the court began to apply to the states, through the portal of the 14th Amendment's due process of law clause, at least those portions of the Bill of Rights that protect fundamental human liberties.

The rest of the book, with the exception of the anomalous war powers chapter, is devoted to cases expounding the protections that apparently are dearest to the authors' hearts. There is a reprise of Near v. Minnesota, involving "an anti-Semitic, anti-black, anti-establishment rag," in which freedom of the press, even an obnoxious press, was firmly upheld. This is followed by a fascinating example of the tension (delicate balance?) that can develop between press freedom and national security. When enterprising journalists learned of the impending Bay of Pigs operation, there arose the well-nigh impossible question of whether the First Amendment must yield to national security interests.

A section on "Protecting 'The Thought That We Hate' " takes up freedom of speech, using as vehicles such cases as the Skokie neo-Nazi parade dispute that, like Near v. Minnesota, demonstrated again the central role in constitutional litigation of utterly wacky people. Later chapters outline the school prayer cases; the morass of search and seizure rulings ; capital punishment; the insanity defense; the birth control and abortion cases; affirmative action and reverse discrimination cases such as Bakke; and the availability of constitutional protections to illegal aliens.

Those who know their Constitution will argue that this is a sampler, not a survey. And they will insist that the authors' omission of numerous constitutional guarantees is unjustified.