Harry Reid is the Majority Leader of the Senate of the United States. He occupies a position of influence at the pinnacle of the American system of government. Of late, the senator from Nevada has become a one-man, First Amendment wrecking crew.

If like Charles and David Koch, your political opinions offend Harry Reid’s ears, or if like the Washington Redskins, your taste in sports-team logos offends his eyes, Sen. Reid will use his office to try to shut you up or make you disappear.

For those who think the Kochs or the Redskins’ logo are unsympathetic victims, think again. The enforcers Sen. Reid is leading will get around to you eventually. In some places, they already have.

Sen. Reid, with Sen. Maria Cantwell of Washington state, outputted a letter signed by a total of 50 Democratic senators and addressed to National Football League Commissioner Roger Goodell. It condemns Washington D.C.’s NFL team and its owner Daniel Snyder for not abandoning the team’s logo, the Redskins.

The letter calls the Washington Redskins a “racial slur.” Sen. Reid has accused the Washington Redskins of a “tradition of racism.” The letter says “Redskins” is the equivalent of the racist remarks of Los Angeles Clippers owner Donald Sterling.

Continuing in this vein of senatorial logic, the 50 members of the world’s greatest deliberative body more or less order Mr. Goodell (“Now is the time for the NFL to act”) to use his power to coerce a name change for Washington’s football team.

Should Commissioner Goodell buckle beneath Harry Reid’s gang tackle, make no mistake: That same Senate letter would go straight to Major League Baseball Commissioner Bud Selig, ordering him, under the Sterling Precedent, to kill the Cleveland Indians’ logo, Chief Wahoo. Were Mr. Selig to do so, there of course would be riots in the streets of Cleveland, whose single most beloved citizen is . . . Chief Wahoo.

In recent weeks, people across the political spectrum professed to be aghast when a small coterie of “offended” students shut down commencement speeches by conservatives, centrists and liberals.

At Smith College, they didn’t want to hear IMF Managing Director Christine Lagarde. At Haverford College, they’d only let former Berkeley Chancellor Robert Birgeneau speak if he signed a letter of apology and guilt for his handling of the Occupy Cal sit-ins in 2011. How, the world of astonished adults wondered, have these students come to believe they could shut people up on any aggrieved whim?

They got it from the Majority Leader of the United States Senate and 49 senators. They got it from the many adults who think a little restriction on some speech is OK, and then cry shock when the mob goes too far. That Senate letter isn’t just about the Washington Redskins. It’s part of a broader, active effort to define and limit what people can say—not just in politics or sports, but anywhere anyone tries to open his or her mouth.

Wonder Land Columnist Dan Henninger on the Senate Majority Leader’s war on the First Amendment. Photos: Getty Images

The New York Times, the New Republic and others have carried articles on the suppressive phenomenon known as “trigger warnings” for college courses. The idea is that professors should post warnings about course content that may “trigger” traumatic memories or thoughts in some students for a list of reasons related to feminist concerns, sex and multiple violations of social justice. Look for a letter soon from Harry Reid to Turner Classic Movies demanding trigger warnings on John Ford westerns.

Last fall at a private party at Lewis & Clark College in Portland, Ore., two athletes—one of them white, the other black—were overheard trading racial jokes during a game of beer pong. Someone reported them to the administration. Lewis & Clark convicted the students of hate speech and ordered them to undergo “Bias Reduction and Bystander Intervention Training.” To their credit, 40 Lewis & Clark professors signed a letter of concern about the school’s notion of due process. American academics must be worrying they may have to go underground to teach freely. We could soon seesamizdat doctoral theses.

In another corner of Harry Reid’s Senate sits an attempt to expand federal surveillance of “hate speech.” Sen. Edward Markey of Massachusetts just introduced a bill called the Hate Crimes Reporting Act. Its purpose, said Sen. Markey, is “to ensure the Internet, television and radio are not encouraging hate crimes and hate speech that is not outside the protections of the First Amendment.” The potential causes of offense are “gender, race, religion, ethnicity or sexual orientation.” In other words, anything.

Sophisticates will recognize that the bill should be better known as the Shut Up Fox News and Rush Limbaugh Act (newspapers are protected from any such regulation). But on their current, unrestrained course, federally deputized talk censors would get around to cleansing and sterilizing MSNBC, too.

We are moving way past the amusements of political correctness. A creeping, even creepy, effort is under way to shut people up for a broad swath of offenses. The distance is shortening between the First Amendment’s formal protections and a “Fahrenheit 451” regime for torching speech in America. The time for adult pushback is overdue.

Write to henninger@wsj.com