Editor's note: Ruben Navarrette Jr. is a CNN.com contributor and a nationally syndicated columnist.
San Diego, California (CNN) -- When is wearing a T-shirt with the American flag on it considered provocative?
Answer: When you wear it to a high school with a dress code that explicitly prohibits "any clothing or decoration which detracts from the learning environment." And when the high school, where 20% of the 1,300 students are English-language learners and 18% come from low-income families, has been described by the San Francisco Chronicle as having "an ethnically charged atmosphere."
And when, despite concerns about potential violence, you and some of your friends make your patriotic wardrobe choices on, of all days, Cinco de Mayo.
Last week, Chief U.S. District Court Judge James Ware said as much when he dismissed a lawsuit by a group of students and their parents against the Morgan Hill Unified School District in North California. The plaintiffs had alleged that, on May 5, 2010, the students' rights to freedom of speech were violated when Live Oak High School Assistant Principal Miguel Rodriguez ordered them to remove or turn inside out T-shirts bearing the American flag. The students refused, and two of them were sent home.
Under ordinary circumstances, wearing a T-shirt with the American flag on it would probably not be a big deal. But this high school is no ordinary place, especially not on Cinco de Mayo. It's a cultural powder keg.
The previous year, in 2009, a group of Mexican students marked the holiday by walking around campus holding a Mexican flag. A group of white students responded by hanging a makeshift American flag from a tree and chanting "USA." According to the Chronicle, tensions flared and the two groups faced off with profanity and threats.
Little wonder that when some students showed up at school wearing T-shirts with American flags on them administrators decided to err on the side of caution.
Meanwhile, the judge did the right thing in dismissing the case and declaring that administrators had the right to take preventive action if there was a "reasonable fear" of violence.
Score one for common sense. Can you imagine where we'd be if the court had gone the other way and stripped school officials of the power to maintain order?
It's easy for conservative radio talk show hosts and other right-wing commentators to criticize the administrators, but they weren't there. They're speaking from ignorance. They don't have even the most basic understanding of the mood at the high school or the events of previous years.
Conservatives are confused. For the last four decades, they have chipped away at the idea that students' free speech rights should trump every other consideration. The Supreme Court established those rights in 1969 in a case called Tinker v Des Moines Independent Community School District.
In that case, a group of high school and junior high school students were suspended when they wore black armbands to protest the Vietnam War. The high court declared that students don't "shed their constitutional rights to free speech or expression at the schoolhouse gate."
But since Tinker, and at the urging of conservatives, the Supreme Court has curtailed First Amendment rights of students, especially when the expression of those rights is disruptive, obscene or might lead to violence.
It did so in three other cases: Bethel School District v Fraser (1986), in which the high court held that a high school student's speech during an assembly -- filled with sexual innuendo -- was not protected; Hazelwood v Kuhlmeier (1988), in which the justices held that schools can regulate the content of student newspapers; and Morse v Frederick (2007), in which the Court held that school officials can restrict student speech at a school-supervised event even if it takes place off-campus.
That's the new legal reality, and it's one that conservatives helped create. Now they have to live with it.
The other problem is the parents, who did their offspring no favors by encouraging them to play the victim and call a lawyer. They were so eager to sue and teach their kids to stand up for their rights that they neglected to teach them that, in our system, rights come with responsibilities.
Like this one: Americans have the responsibility to treat one another, and one another's cultures, with respect. Just because someone shows cultural pride -- St. Patrick's Day, anyone? -- doesn't mean it's an expression of anti-Americanism. Quite the opposite. America is all about coming together as one, while preserving the cultural attributes that make us unique.
There's the rub: The students who brought the lawsuit against school officials claim to be proud of the American flag. But it's obvious they don't have the foggiest idea what it represents. And, when they had the chance, their parents failed to teach them.
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The opinions expressed in this commentary are solely those of Ruben Navarrette Jr.