MORGAN HILL — As they pick at a few egg rolls at their favorite Chinese restaurant on the outskirts of town here, Kendall and Joy Jones and Dianna Dariano recall Cinco de Mayo in 2010 — and it still makes them seethe red, white and blue.

Capturing the nation’s attention and sparking a patriotic backlash, their sons were ordered by Live Oak High School administrators to turn their American flag-adorned shirts inside out to avoid any conflict with Mexican-American students celebrating Cinco de Mayo.

In many ways, everyone has moved on. The boys have gone off to college. The principal and assistant principal involved have left Live Oak. The Fox News trucks are long gone from the school’s parking lot.

But the controversy simmers, reaching a crucial stage Thursday, when a federal appeals court considers the families’ free speech lawsuit over the incident. The 9th U.S. Circuit Court of Appeals will hear arguments in the parents’ appeal of a ruling last year dismissing their case.

The parents still want the Morgan Hill Unified School District to be held accountable for what they consider an unpatriotic violation of the students’ First Amendment right to wear an American flag on a T-shirt on any day of the year.

“It’s the principle of the thing,” Kendall Jones says. “We don’t want anybody else to go through what these kids did.”

Adds Dariano, a Latina, “Do not say to anyone in the United States you can’t wear an American flag. That’s an absolute outrage.”

Despite striking a public chord over the episode three years ago, the families and their legal claims have encountered substantial resistance.

Morgan Hill school officials argue that the Live Oak administrators’ actions were a necessary safety precaution because of a history of campus strife between Hispanic and Anglo students on Cinco de Mayo. They maintain that safeguarding students trumps free speech concerns.

“This is not a case about the flag, or the First Amendment rights of adults in a public forum,” the district said in court papers. “This is a case about whether we allow school administrators, familiar with the circumstances in their schools, to take reasonable steps to protect student safety in the face of threats and a history of violence.”

A federal judge last year agreed, siding with the school district’s arguments by dismissing the lawsuit. Former Chief U.S. District Judge James Ware acknowledged that students have free speech rights, but school officials have the power to intervene if there is the potential for a “substantial disruption” on school grounds.

Morgan Hill Unified and Live Oak administrators did not respond to requests for comment. Don Willenburg, the district’s lawyer, declined to comment, other than to say that Ware “got it right.”

The details of the incident are largely undisputed. Daniel Galli (the Joneses’ son), Matt Dariano, Dominic Maciel and at least two other students showed up to school with American flag images on their shirts. The boys were not, according to their parents, trying to incite trouble, but wanted to express their patriotism.

“Like any good sports fan, they were supporting their team,” Kendall Jones said. “It wasn’t a political statement against anybody. The boys just wanted to display their colors.”

School officials, however, thought otherwise, particularly because just a year earlier there had been major disruptions on Cinco de Mayo at the diverse south Santa Clara County campus. A Live Oak assistant principal hauled the boys in and told them to either turn their shirts inside out or go home.

The decision provoked chaos at Live Oak for days, as media crews descended to spotlight the American flag flap. The students received threats. Within a week, the campus united to hold a peaceful rally to end all the strife.

Nick Boden, then Live Oak’s principal, conceded days after the episode that the reaction to the T-shirts may have been a somewhat hasty overreaction. Boden, who has retired, could not be reached.

But the parents never got what they wanted from Morgan Hill Unified — an apology and a promise that no student would ever again be barred from bearing an American flag on their clothing. As a result, they’ve pressed the lawsuit, backed by conservative legal groups.

“American public schools cannot logically ban the American flag for any duration or reason,” the parents’ lawyers told the 9th Circuit.

Legal experts see tough questions in the case, pitting the right of high school students to express their views — rights even stronger under California law — against the indisputable right of schools to ward off violence.

Ware’s decision may be correct, said Eugene Volokh, a UCLA law professor and free speech expert, although he added: “That’s too bad. In a sense, it’s a heckler’s veto.”

The families, meanwhile, are ready to take their cause to the U.S. Supreme Court. The boys are letting their parents do the talking at this point, although they are paying close attention. The Joneses’ son, Daniel, is attending the University of Nevada, Reno, and plans to become a lawyer, fueled in part by his experience at Live Oak.

“I was going to make sure we were not going quietly,” Kendall Jones said. “They weren’t going to sweep this under the rug. We want accountability.”

Howard Mintz covers legal affairs. Contact him at 408-286-0236 or follow him at Twitter.com/hmintz