The school has not yet responded to a request for comment.
Parkway is part of the Bossier Parish School System and their superintendent Scott Smith says when a student joins a team, the players and coaches should stand when the national anthem is played to show respect.
"This is antithetical to our values as Americans and a threat to students' constitutional rights", ACLU of Louisiana Executive Director, Marjorie Esman, said in an online statement, condemning both Bossier Parish School District and Parkway High School.
The previous day, the principal of Parkway High School sent a letter to student athletes warning them not to mimic the widespread protests that took place over the weekend at National Football League (NFL) games.
Both were well written articles that were interesting, informative and certainly timely. Her son, Kameren Ashley, said that he and a teammate silently protested police brutality during the anthem at a game a year ago by turning their backs to the flag. "These laws must, to be consistent with the First Amendment, permit the widest toleration of conflicting viewpoints consistent with a society of free men". If a protest is not disruptive, public schools have to allow it. "The problem is, there have been judges who are willing to look the other way on the First Amendment inside a school". You might not even be on the team anymore. And in 1969, a 7-2 majority in Tinker v Des Moines School Board clarified the rule. "It's not about the flag, it's about the constitution, knowing your rights, and being able to protest peacefully".
Given the court's decisions, other public schools are issuing memos re-affirming students' right to kneel. Schools have no valid interest in turning their students into mouthpieces of government speech, full stop.
"The least Bossier Schools can do is expect our student athletes to stand in solidarity when the National Anthem is played at sporting events in honor of those sacrifices", he said. In that case, the justices ruled a principal could censor yearbook stories about divorce and teen pregnancy because students' articles were sponsored by the school.
The Acadia Parish School Board is also leaving the handling of protests during the anthem to its school principals and head coaches. "It's freedom of speech, freedom to express yourself", said parent Wally Cisnero.
"Schools should regard understudies who grasp their sacred rights and confront treachery - not rebuff them".
This hasn't stopped schools from penalizing individual students before: as Education Week points out, then-14-year-old Leilani Thomas, who is Native American, had her participation grade brought down last year in class for sitting during the Pledge of Allegiance, something she had been doing since second grade.
One school in Louisiana threatened students who choose to kneel during the national anthem, but Shelby County Schools in Memphis is taking a different course of action.
"I think the answer is to be respectfully tolerant in a difference in political opinions and to use that demonstration as the opening for bigger conversations", he said.