The campus free-speech debate has found a new home — the university library. At Harvard, where I teach, about 30 students staged a silent “study in” in the main reading room of Widener Library last month to protest the war in Gaza. The students, wearing kaffiyehs and displaying “Imagine it happened here” signs on their laptops, broke the rule against using library spaces for protest; the library responded by suspending their access to the main building for two weeks. Earlier this month, a group of two dozen or so faculty repeated the study-in, this time wearing black scarves and championing civil disobedience. The ensuing uncertainty — what should the library do now? — poses a fascinating free-speech problem.

On the one hand, everyone recognizes the appropriateness of what are called “time, place and manner” restrictions on speech. You can’t blare loud music on a residential street at 3 o’clock in the morning as an act of protest. And you aren’t supposed to block rush-hour traffic on Massachusetts Avenue (or 42nd Street) with your protest, either.

Time, place and manner restrictions rest on two basic principles. The first is noninterference: Your ability to speak freely is limited by your responsibility not to interfere with the basic purposes of the time and place in which you are speaking. A busy thoroughfare exists for the free movement of traffic, especially during peak commuting hours.

The second bedrock principle of time, place and manner restrictions is that they don’t target what you say, but only when, where and how you’re saying it. To use terminology that the Supreme Court has occasionally employed, the government must not be trying to suppress certain ideas or messages based on their content.

This principle requires that, when it comes to time, place, manner restrictions, all speech be treated the same. If the library’s rule against protest is based on time, place, manner, then the professors’ study-in can't be treated differently than the students’ based on content. There would have to be some material difference in what they did. (Unless there were a good reason to treat students and faculty differently in this context, which there isn’t.)

So the principles are straightforward and not controversial. But when it comes to implementing them, things get a little less obvious.

From the perspective of the university when it gave the students their (essentially symbolic) punishment, it makes sense to say that the purpose of the library is to research and study, not to make collective statements. Seen from this point of view, a rule prohibiting collective protests in the library is a classic example of a reasonable time, place and manner restriction. There are plenty of other places in the university where the students can protest — including the front steps of the library, where you get a much bigger audience.

Put another way, the university’s response is based on the idea that holding a protest in the library, even a silent protest, interferes with the use of the library. Anyone who happened to be in the library during the protest would have noticed and might have been distracted from their research or study. Presumably that was the point of the protest.

The protesting students and faculty, however, are exploiting a distinctive feature of the library that needs to be taken seriously: Ordinarily, as long as you are sitting at your desk silently, you can do whatever you want there. No one checks to see if you’re preparing for class, reading your email or doodling in your notebook. Consequently, as two of the professors who staged the protest claimed, “sitting quietly and reading simply cannot be classified as disruption. This is true regardless of the clothing people wear or the stickers, reading materials or printed sheets of paper they independently or collectively have with them.”

You can see why the study-in approach is so clever: If silence is the only rule of non-disruption in the library, then disallowing silent protest doesn’t look like a time, place and manner restriction. It looks like it’s aimed at what people happen to be expressing by their particular type of silence, defined by their intention, their outfits and what stickers or signs they have with them. If non-disruption is defined by the attention-getting purpose of your (silent) conduct, then the no-protest rule really is a legitimate instance of permissible time, place and manner restriction.

Libraries are, or should be, the crown jewels in the research university. I love Widener Library more than almost any other place on earth. A few years ago, as part of a get-to-know-you exercise, I was asked to submit a picture that means “home” to me. I sent an image of the 6-East wing of the Widener stacks.

But all my love of the library doesn’t definitively answer the question of whether silence is the only non-interruption rule there. The right solution is for the library to think about the issue more deeply, perhaps by appointing a committee of people who love and use the library to hash it out and recommend a rule that will work in theory as well as practice.

In terms of protecting the library’s true purpose, my instincts favor keeping protests outside. And I tend to favor free-speech approaches that are attuned to the social meaning of symbolic conduct over those that ignore context. Nevertheless, in practice, my strong hunch is that a rule allowing silent protests in the library would immediately end the protests taking place there. After all, the point of protest is to get a reaction. Here, the university’s response, not the protests, is generating attention. Without it, there would be no reason for anyone to do anything in the library but sit, read and think. And doodle.

Noah Feldman is a Bloomberg Opinion columnist. A professor of law at Harvard University, he is author, most recently, of “To Be a Jew Today: A New Guide to God, Israel, and the Jewish People.”