When Bay Area Rapid Transit officials shut down cell-phone service on the train platforms last week, they believed they were averting a disruptive protest. Their actions also triggered a number of questions about whether they had violated the First Amendment.

BART is a California government agency and subject to the First Amendment. The Constitution guarantees that government may not limit our free speech.

But is it unconstitutional censorship when government pulls the plug on technology? BART maintains that it was attempting to protect public safety by heading off a protest over the shooting of a man by a transit police officer, a demonstration the agency maintains is prohibited by its rules.

BART also claims it has the right to control technology on its premises. Some key First Amendment questions stemming from BART’s actions:

• Is a BART train station a public forum? The agency contends that it cut off cell-phone service only to prevent prohibited activity, but the planned protest may in fact have been protected as constitutionally guaranteed assembly. A California Supreme Court decision in 1967 found that a city could not ban peaceful political activity inside a railroad station.

• Did BART intend to suppress speech by shutting off cell-phone service or was it simply trying to run a railroad?

• Was the agency’s restriction on communication content-neutral? Courts have frequently upheld actions of government designed to maintain public order or safety when all speech is affected and no point of view is singled out. Yet BART’s actions were designed to prevent people from talking about staging the protest, a specific subject.

• Did BART have a right to limit incoming ideas? There’s a tendency to view freedom of speech as the right to share your opinions, but there’s also a First Amendment right to receive the ideas of others. BART points out that the agency only recently made cell-phone service available. But once service is in place, can the agency cut off the free flow of texts, emails, and messages flowing to passengers who had absolutely nothing to do with the protest? These days, every cell phone with a Twitter feed or news app is in effect a self-contained digital printing press.

Critics of BART’s actions have compared the agency to Hosni Mubarak, who cut off communications in Egypt in an attempt to maintain his regime. The difference, of course, is that there was no First Amendment to rein in Mubarak. In the United States, government agencies have to play by the rules contained in the Bill of Rights.

Ken Paulson is president and chief executive officer of the First Amendment Center. Previously, Paulson served as editor and senior vice president for news of USA Today and USATODAY.com.