This is not a new problem. Polybius, in his history of the Roman republic, complained that the Romans lost interest in freedom of speech:
But as soon as a new generation has succeeded and the democracy falls into the hands of the grandchildren of its founders, they have become by this time so accustomed to equality and freedom of speech that they cease to value them and seek to raise themselves against their fellow citizens, and it noticeable that the people most liable to this temptation are the rich.
So, he says, people hankering after office and not qualified to succeed on their own merits begin to seduce the people with bribes. Our campaign finance system is the modern reflection of the unstable situation Polybius described, where the wealthy bribe the powerful with soft money and the powerful then bribe the people with empty promises of freedom from want or from taxation, from minorities or the powerful, or whatever the bugaboo of the day is.
De Tocqueville had a remarkably similar insight into the American political situation. "One encounters in the human heart a depraved taste for equality," he remarked, "which drives the weak to wish to pull the strong down to their level, and which reduces men to preferring equality in servitude to inequality in liberty":
It is not that people whose natural social state is democratic naturally feel contempt for liberty; on the contrary, they have an instinctive taste for it. But liberty is not the principal and continuing object of their desire; that which they love with an eternal love, is equality; they rush towards liberty by rapid impulses and sudden efforts, but, if they miss the goal, are resigned to it; but nothing can satisfy them without equality, and they would rather die than lose it.
To put it somewhat differently, liberty is something of an intangible, procedural goal, while equality is manifested much more tangibly, in status, creature comforts and the like. It is human nature that the substantive will trump the procedural, and this is in fact one of the main problems of our constitutional law. It is hard for people who believe a convicted murderer deserves to die to care about the procedural flaws that denied him a fair trial. Similarly, people who hate the content of particular speech-- neo-Nazi propaganda or flag desecration, for example--do not understand why a process that protects such speech is inherently valuable to us all.
This too is not a new problem. I highly recommend Leonard W. Levy's Emergence of a Free Press, which uncompromisingly examines the hypocritical conditions in which the American system of freedom of expression was born. Freedom of speech was resolutely claimed during Colonial times, but its advocates saw it as a means to attainment of their goals, not an end in itself, as they proved by smashing the presses of pro-British printers during the revolution and by prosecuting royalists and other adversaries under the Alien and Sedition acts afterwards. Benjamin Franklin, whose own brother had faced prosecution under the colonial government for printing revolutionary opinions, declared himself completely comfortable after independence with the common law of seditious libel, which allowed the new government to prosecute its adversaries for their ideas. Levy wrote, "The American people simply did not believe or understand that freedom of thought and expression means equal freedom for the other person, especially the one with hated ideas." And neither do they today.
Freedom of speech is really a philosophical value, set in a setting so political that, for the reasons described by Polybius, powerful forces are always working to defeat it. The desire to attain power and the desire to protect free expression part company when power is attained; and the public's desire for equality, benefits and material comforts is the vulnerability the power-seekers exploit to attain their goals. As I have written elsewhere, our systems of freedom of expression is a sort of rulebook like the Marquess of Queensbury rules that tell boxers, "You must not fight simply to win; no holds barred is not the way; you must win by the rules." In the U.S., since the desire of elected politicians is to win, increasingly at whatever cost, it is the appointed judicial branch who must serve as philosopher-kings, protecting the procedural and the weak against the depradations of the substantive and strong. But, since the judges themselves are political appointees, approved by the Senate in an increasingly politicized process, and as of recently, threatened with impeachment for their so-called "judicial activism", the prospects are not always grand that they will be willing, or able, to do their job.
It is relevant here that there are many people who believe that the courts, including the Supreme Court, should have no right to void an act of Congress--a belief which if adopted would greatly hasten the end of our procedural liberties.
Contrast the strong words of Justice Holmes, architect of the "marketplace of ideas" metaphor for American freedom of speech, who contemplated (in his dissent in Gitlow v. NY) the possibility that bad speech might win the market struggle:
If in the long run, the beliefs expressed in proletarian dictatorship are destined to be accepted by the dominant forces of the community, the only meaning of free speech is that they should be given their chance and have their way.
The philosophical underpinnings of the free speech rulebook are humility, tolerance and optimism--the humility to understand that our own ideas are not absolute truth, tolerance for the ideas of others even if we do not understand or are appalled by them, and optimism that free expression, as a process, will work out for the best in the end. The latter is what Holmes really meant; he did not believe that dialectical materialism would triumph, and it has not. But humility, tolerance and optimism are the first qualities we abandon when we seek power or are bribed by those who do. This fundamental struggle in ourselves is what guarantees, to borrow Robert Frost's phrase, that "nothing gold can stay."