Freedom of speech is a cornerstone of democratic government. It should be - and, in the United States, is - constitutionally protected. Governmental moves toward limiting speech or imposing censorship are generally telling signs of an attempt to curb democracy. Such acts must be guarded against and rebuffed, if a society is to stay free.
Sometimes, however, it is possible to mistake unchecked expression for free speech. They are not one and the same. To use the classic example: One has no inherent constitutional right to scream ''Fire!'' in a crowded theater when there is no fire. In fact, such action may result in a civil or criminal penalty - particularly if it represents a deliberate attempt to incite a riot.
What actually constitutes free speech and, therefore, is protected under the First Amendment is not always easy to determine. Lawyers, scholars, courts, and legislators, among others, continue to debate this question. Some would apply a test of ''truth'' or ''fact.'' Intent may be a consideration. And questions of ethics or public standards often surface.
Several tough cases in this area are now before the courts. They involve news-media responsibility and the public's right to know, as well as limits on the expressions and actions of individuals. The resolution of the cases won't end the debate over protected speech, but new yardsticks may be set up.
One of most highly publicized and highly priced libel suits of the decade - retired Gen. William C. Westmoreland's suit against CBS - raises the question of whether the press is wholly protected by the First Amendment in its critical reporting of the Vietnam war.
The network alleged in a 1982 television documentary that the general and others ''conspired'' deliberately to distort estimates of enemy forces in Vietnam in order to convince the American public that the US was winning the war. The case is unusual because it will have the effect of bringing to the courtroom the bitter national controversy over that war. In terms of legal precedent, if the federal court decides in favor of General Westmoreland, it would be the first time a high-ranking military figure or former official was successful in suing the media for statements made about his performance in office.
Under current libel standards, however, Westmoreland must show that CBS's statements constituted ''actual malice'' and were made with a ''reckless disregard for the truth.'' Since Westmoreland is considered a ''public figure'' by the courts, the network need not show absolute accuracy in its reporting.
This case sends chills down the spines of many media moguls - not only because of the huge amount of the claim but also because a judgment for the plaintiff could, they say, tend to deter investigative reporting and, hence, encumber free speech exercised in the form of criticism of government policies.
Another case, not yet in court and less well publicized, also raises a potentially serious issue regarding legal sanctions on the press. R. Foster Winans, a former Wall Street Journal columnist, has been indicted by the Justice Department on fraud and conspiracy charges. He and others allegedly benefited from inside financial data he possessed when he leaked information from forthcoming columns to associates who were able to profit from it.
Mr. Winans was fired for his admitted impropriety. But the government has charged that he committed criminal acts, holding that the newsman had a legal ''duty'' to his editors and readers to disclose his interest in stocks he was writing about. First Amendment protectors say they do not condone the reporter's action - but many balk at the notion of government-enforced responsibility to readers. And they say that the idea of a ''fiduciary obligation,'' if embraced by the courts, could dangerously abridge freedom of speech.
Regarding speech protections for individuals, the US Supreme Court has agreed to look further into this area with cases involving obscenity and homosexual advocacy this term.
The court will review a Washington State ''moral nuisance'' law that defines prurient interest in terms of inciting lasciviousness. In 1973, the high court ruled that the First Amendment does not protect speech that ''... appeals to the prurient interest'' as seen by ''contemporary community standards.'' New curtailments on obscene speech are likely to result, if the Washington State statute is upheld.
An Oklahoma statute is at stake in a school case involving homosexual advocacy by teachers. The Supreme Court must decide whether such a stance falls under the umbrella of constitutionally protected free speech. A state law permitted school districts to dismiss a teacher for ''advocating, soliciting, imposing, encouraging, or promoting public or private homosexual activity in a manner that creates substantial risk that such conduct will come to the attention of schoolchildren or school employees.'' But an appellate court decided that parts of the statute dealing with ''advocacy'' were overbroad and invalidated them.
There are built-in risks in limiting any speech in a free society. But there is also a serious danger to society if courts decide to elevate expression that is offensive to public sensibilities to the level of a constitutional right.