At journalism school I flunked my class in “Trends: How to Identify Them, How to Invent Them.”

So I’m not qualified to peg what follows as a genuine social or cultural trend. But it’s happened in four state legislatures already. And we can always hope.

Most recently it’s been percolating in Missouri, where Rep. Jane Cunningham introduced a bill that will surely unnerve many of her state’s higher education bureaucrats.

Ms. Cunningham’s bill is aimed straight at the ideological orthodoxy that holds sway on American college campuses. It would require that Missouri’s state-funded colleges and universities announce each year what they have done institutionally “to ensure and promote intellectual diversity and academic freedom.” A bill similar to Ms. Cunningham’s has also been introduced in Virginia.

In 2005, the state legislature in Pennsylvania established a special committee to investigate academic freedom and intellectual diversity on its campuses. The committee is requiring Pennsylvania’s public colleges and universities to report by November 2008 on what concrete steps they’ve taken to ensure “student rights” with respect to intellectual diversity.

And the South Dakota Board of Regents, responding to a similar move by its state legislature, now requires that a so-called Academic Freedom Statement be included in all course syllabuses, informing students that only academic performance, and not their political opinions, will serve as a basis for their grades.

Missouri, Virginia, Pennsylvania, South Dakota — as they go, so goes the nation, maybe. This might be a trend after all. Or at least a trendlette.

Credit for it goes in part to the lobbying efforts of the American Council of Trustees and Alumni, a Washington-based academic watchdog group dedicated to the proposition that “the lack of intellectual diversity is the greatest problem facing higher education.”

Like a lot of activist groups in the American conservative movement, ACTA specializes in taking the categories and phraseology of its ideological adversaries and turning them inside out.

Thus the progressive shibboleth of diversity — most often used to indicate an unseemly obsession with racial categories and sexual orientation — is now being used for something more admirable and democratic.

It’s meant to promote a range of intellectual views in institutions, many of them supported by taxpayers, where such a range is conspicuously lacking thanks in part to the efforts of administrators and professors who are obsessed with their more narrowly defined brand of diversity.

The data describing higher education’s monochromatic ideological tint are hard to ignore — and they intuitively ring true to anyone who’s spent much time on a college campus.

In 2003, Daniel Klein of Santa Clara University and Charlotta Stern of Stockholm University conducted a large-scale survey of six national associations of social science and liberal arts faculty. The ratio of Democrats to Republicans ranged from 30-to-1 among anthropologists to 3-to-1 among economists.

More recently, a survey by sociologists Stanley Rothman, S. Robert Lichter, and Neil Nevitte found that roughly 80% of humanities professors described themselves as left of center and 5% said they were conservative.

In the face of this evidence, defenders of the academic status quo have moved from arguing that the ideological tilt doesn’t exist to arguing that, if it does exist, it has no practical effect.

You would have a hard time proving that by Lawrence Summers, of course. Even a mainstream liberal like the former Clinton Treasury secretary had to quit the presidency of Harvard after he offended the ideological orthodoxy of the university’s humanities faculty.

But what about abuse and intimidation in the classroom? Here the evidence, both statistical and anecdotal, is thinner though still unsettling.

Members of the Pennsylvania committee cited “dozens” of letters from state students complaining about professors who enforced an ideological conformity in the classroom. Others cited a tilt in the paid speakers invited to campus or school-sponsored panels on current events as well as a generally inhospitable atmosphere for public conservatives.

ACTA commissioned the Center for Survey Research and Analysis at the University of Connecticut to survey undergraduates at the top 50 colleges and universities. Their majors ranged from the humanities to the hard sciences.

Almost one in three, 29%, said they felt pressure to agree with their professors’ political views to get a good grade.

Another 42% said that classroom assignments on controversial subjects were “one-sided.”

In light of these rumblings, and faced with the vast uniformity in the ideological coloration of the faculty, the steps being called for in the state legislatures, and by ACTA, seem reasonable enough.

Among them: letting students know during school orientation that they have means for filing grievances if they’ve been politically intimidated; including questions about “academic freedom” on student course evaluation forms, and keeping a central record of academic freedom complaints.

Mild measures like these fall rather short of “McCarthyism.” But predictably enough, it is “McCarthyism” — the off-the-shelf, all-purpose debate-ender — that ACTA and the legislators are accused of by the defenders of the academic status quo.

Really, these people need to find a new cliche to hurl at their critics. If they do, I’ll be happy to declare it a trend.

Mr. Ferguson is a columnist for Bloomberg News.