These policies are most likely unconstitutional, but there have been no major legal opinions issued as of today (August 8, 2016.) However, a Texas high school student has sued his school district for suspending him for defending himself against violent bullies, and the case is pending.
In the landmark decision Tinker v. Des Moines School District (1969), the US Supreme Court ruled that students do not "shed their [Constitutional] rights at the schoolhouse gate." Self defense is a constitutional right -- research the 9th and 14th Amendments. Therefore, according to the Supreme Court, which, by the way, is NOT the "final arbiter" of the Constitution (link), "anti-bullying" policies that prohibit self defense are unconstitutional.
However, schools have little respect for the fundamental rights of students, and enforce politically motivated "zero tolerance for fighting" policies that punish victims rather than bullies. Here are a few examples:
1. At River Road Middle School in Elizabeth City, NC, a 6th grade honors student was suspended from school for using force against attackers who repeatedly punched him and pushed him to the ground. (Source)
2. In Carrolton, Texas, bullies assaulted a victim in the school showers. The victim hit the attackers in order to escape. When the school administration was made aware of the incident, everyone involved was suspended from school, including the victim, who has now filed a lawsuit. (Source)
3. At Savannah High School in Georgia, a student was suspended for fighting back against a violent gang of attackers who "came off the street, into the cafeteria, and started beating him up." The principal of the school claimed "that it takes two to fight", ignoring the clear, indisputable fact that the victim was assaulted and backed into a corner by a violent gang. In addition, Georgia has a "Stand your Ground" law, a law that strengthens self-defense rights in public places. The law was apparently ignored by the school, but it appears that the victim has not filed a lawsuit. (Source)
4. In Horry County, South Carolina, a 7th grade student was knocked to the ground and hit in the face several times. When he defended himself, he was suspended from school for 2 days. There were witnesses to the fact that all he did was defend himself, including a police officer, but the school suspended him nonetheless. (Source)
5. In Charlotte, North Carolina, a 12-year-old was suspended from school for pushing his attacker away while he was being hit over a dozen times, thrown to the ground, and given a concussion. His parents, wisely, pulled him out of the school. (Source)
6. At a school in Raleigh, North Carolina, a 16-year-old girl was suspended from school, placed in an "alternative educational program", and charged with two counts of "simple affray" for defensive actions. (Source)
7. In a Fort Myers, Florida school, a 16-year-old student wrestled a loaded gun away from a fellow student who pointed the gun at a classmate. Instead of celebrating him as a hero, the school district slapped him with an "emergency suspension" for taking part in an "incident involving a weapon."
These policies are not just inimical to the Constitutional right of self-defense, which dates back to Roman law. Public school "anti-bullying" policies that disallow self defense also protect bullies. Self defense is a deterrent to violence. If students are forced to simply stand and allow violence to be inflicted on them, bullies are not deterred, and likely will pick on them again.
Public schools must immediately recognize the right of self defense, and reverse all past penalties such as suspensions for students who acted in self-defense. In addition, schools must erase all penalties for self-defense from students' "permanent records."
"The right of self defense is the first law of nature."
- Blackstone's Commentaries on the Laws of England, 1803