As James Madison, the father of our Constitution, put it: "If men were angels, no government would be necessary." In other words: if men and women never erred, lied or had to struggle to arrive at ever-changing truths, the need for dissent and due process might be somewhat diminished. But that is not our world. We are a deeply divided people and in sharp disagreement over the most important issues. There was never a time when dissent and due process were more essential to governance. And there has rarely been a time when these values have been more under attack by decent people with admirable goals. But as Justice Louis Brandies once cautioned: "The greatest dangers to liberty lurk in the insidious encroachment by men of zeal, well meaning but without understanding."

Moreover, these recent attacks are more difficult to combat because they come for the most part from the private sector rather than from government. Private censors and deniers of due process are not constrained by the Constitution. They generally have their own rights to do wrong things. We must combat them in the courts of public opinion rather than in the courts of law.

For more than half a century I have been litigating and winning freedom of speech cases against the government in the courts, including the Supreme Court. We had the First Amendment on our side and that gave us the advantage. Today, big tech, private universities and progressives have the First Amendment on their side—even when they are censoring based on content. The Supreme Court has ruled that private media companies have a First Amendment right to pick and choose what they will publish, including not giving a person they attacked the right to respond and set the record straight. They, like other private parties, have the right to be wrong and to do bad things in the name of freedom of speech.

In an effort to show that they are not doing bad things, Facebook has appointed its own "court" to review its censorship decisions. Its first high-profile "case" involved the banning of a president, now former president, Donald Trump, following his constitutionally protected, though ill-advised speech of January 6, 2021. Facebook's review board "ruled" that the ban was proper, but had to be reviewed within six months. This decision satisfied no one. Opponents of the ban thought six months was too long; proponents thought it too short. I, for one, am worried about giving any court—even a fairly balanced one, which this is not—the power to decide what we should read, who we should listen to and what should be banned.

YouTube doesn't have its own Supreme Court. It makes its own decisions without external review. I recently suffered "collateral damage" from a YouTube decision to censor. I debated Bobbie Kennedy—the son of the former attorney general and an environmental lawyer—about vaccination. He is a skeptic and raised some interesting points about the current vaccines. I disagreed and we politely argued back and forth. Thousands of viewers watched the debate—until YouTube took it down because of some things that Kennedy said, to which I responded. But YouTube didn't trust the marketplace of ideas, so it canceled the debate.

This is the way of the future—unless we do something about it.

Follow Alan Dershowitz on Twitter @AlanDersh and on Facebook @AlanMDershowitz.