Last week, a vice principal at a California high school disciplined several students for wearing American flag t-shirts to school. Yes, you read that right. The reason that this symbol of our great nation was transformed into a reason for detention? The students wearing them intended the flags to express a point of view – they wore them on the day of the school’s celebration of Cinco de Mayo, honoring many students’ Mexican heritage.

These kids intended their t-shirts to say something political: that they had a point of view that did not conform with that of the school or their classmates. In expressing this on Cinco de Mayo, their clothing took on a deeper meaning: a symbol of politics, patriotism, and dissent, therefore deserving of the First Amendment’s full protection.

Fortunately, cooler heads at the school district took immediate steps to make sure the students were not punished for wearing the colors of the USA, but the ACLU of Northern California is rightly concerned about a school culture where such censorship remains a possibility. This incident certainly calls into question how we got to such a place: how could our nation’s own flag be seen as a possible source of disruption in an American public school – a place where kids salute one every day?

This case is part of a long tradition of high school students exercising their First Amendment rights. In the 1970s several Iowa high school students, disciplined for coming to public school wearing black armbands in protest of the Vietnam War, took their free speech case all the way to the U.S. Supreme Court, which famously noted in its opinion that students “do not shed their constitutional rights at the schoolhouse gate.” The Court held that students have a First Amendment right to express themselves so long as that expression is not disruptive to the school day.

In reality, schools are a tightly regulated, sometimes sterile environment. The opportunities for non-disruptive speech are few and far between. No soapboxes in the cafeteria. No sandwich boards in crowded hallways. No political diatribes in algebra class. What’s left for a public school student who wants to retain his individuality, or express her opposition to a government policy? The free, silent ad space between their shoulders: the message-bearing t-shirt.

Unfortunately, many school officials and culture warriors have been on a mission to eradicate even this one vestige of student choice. They argue for school uniforms, based on flawed arguments about school safety, gang colors, and ‘useful’ conformity. This approach will undoubtedly lead down a slippery slope where student clothing need not be ‘disruptive’ so much as ‘potentially upsetting to someone (i.e., a teacher) in theory.’ It is not hard to see how in this environment, administrators might become the t-shirt police, and imagine disruption where none exists – even among the stars and stripes.

It is critical that we stop infringing on students’ last opportunity for truly free speech, and let them take advantage of their clothing to express themselves. And even, sometimes, make people a little uncomfortable. Democracy – especially one springing from our beloved First Amendment and its principles– is messy. We aren’t doing our young citizens any justice by pretending otherwise in school by sterilizing and scrubbing all speech.

So let us pause and give thanks for the t-shirt: the last possible refuge of free speech in the public schools, the walking student billboard, the one medium that permits students to retain – and broadcast – some sense of self and politics even in the school environment. Our student citizens deserve a protected medium of expression, and those California high schoolers should be saluted for being the standard bearers of both the U.S. Flag and the U.S. Constitution.

Lee Rowland is the ACLU of Nevada's Northern Coordinator.