I’ve noticed that people tend to only hear about campus free speech cases which fit their particular narrative (either of conservatives censoring liberals or of liberals censoring conservatives). Apolitical cases (for instance, Valencia College’s censorship of students who protested forced transvaginal ultrasounds) tend to become less widely known, as do cases of liberal censorship among conservatives and conservative censorship among liberals. In addition, people hear more about cases of censorship at famous colleges (such as Harvard or Yale) than they do about the less famous colleges that most people actually go to.
The Foundation for Individual Rights in Education is a well-respected organization which specializes in campus free speech and other civil liberties. My sample was the list FIRE maintains on its website of cases it has worked on in the past (for instance, by sending the college a letter or engaging in litigation). I took every fifth case and coded it as censorship of conservative, censorship of liberal, or apolitical censorship. There were 88 cases in my sample. I dropped five for being FIRE suing about bad policies with no clear indication of whom they would be used against, four for being sexual misconduct policies (which are not instances of censorship), and two for being miscellaneous instances of inadequate college due process (which, again, are not censorship). This left me with 77 cases.
Of the 77 cases, I coded 20 (26%) as censorship of liberals, 40 (52%) as censorship of conservatives, and 17 (22%) as apolitical censorship. An example of censorship of conservatives is refusing to allow Christians to organize a student group; an example of censorship of liberals is not allowing PETA supporters to hand out flyers; an example of apolitical censorship is suspending a professor for saying, during a review session for a test, that the questions he was asking were so difficult he was on a killing spree.
I made a few judgment calls which I want to discuss. One instance of a hate speech code was coded as “censorship of liberals” because surrounding discussion suggested it was intended to censor pro-Palestinian, anti-Israel protests. While some people would consider sexual harassment law to be inherently liberal, I classified (for instance) the censorship of a crew team’s shirts saying “check out our cox” as apolitical censorship, since lewd puns are not a political sentiment. (Of course, if sexual harassment law was used to censor a political statement, I classified it as “liberal” or “conservative.”) I classified socialists as liberal and libertarians as conservative, in spite of both groups’ probable objection to such a classification. “Nationwide disinvitation of speakers,” a single FIRE case, was classified as conservative because 9/10 of the most disinvited speakers are conservative, but note that Bill Ayers is also on the list. (It is also a judgment call that I (a) didn’t treat each disinvitation as a separate case and (b) included “nationwide disinvitations” at all.)
ETA: I’d also like to note that the Foundation for Individual Rights in Education is not a random sample of college censorship cases. Presumably they do not pursue every case brought to their attention, and there may be systematic biases in which students contact FIRE. For example, conservative students may trust FIRE more and be more likely to call them when campus censorship occurs, or conversely FIRE may pursue more cases of liberal censorship to combat its image as a defender of the right wing. These results should be taken with a grain of salt.
In conclusion: there is a definite tendency for censorship on college campuses to be censorship of conservative viewpoints, perhaps because conservative viewpoints tend to be underrepresented in academia. However, about a quarter of college censorship in this sample is of liberal viewpoints and a quarter is of apolitical viewpoints; this suggests it is a mistake to assume that censorship on college campuses is solely of conservative viewpoints. However, given the limitations of my data, I’d strongly advise against drawing any conclusion from it firmer than “censorship of both liberals and conservatives occurs on college campuses, and conservatives probably face more.”