When children sexually assault other children at school, sometimes the only measure of justice comes through the courts.
 
    The barriers are formidable, and can lead to long, grueling fights: Public schools in many states enjoy powerful shields, including caps on damages and high legal hurdles to prove misconduct. And a handful of states offer schools complete immunity from lawsuits in state court.
 
    But the incentives for families are powerful, too -- protecting their children, winning reforms and sparing others the nightmare of sexual assault.
 
    A Miami mother sued in 2012 after she said her second-grader was repeatedly abused by an older boy at his charter school. Eventually, the 7-year-old tried to kill himself by walking into traffic with his eyes closed, according to the family's lawsuit. Two years later, the little boy testified, he still had nightmares his tormenter would crawl in through his bedroom window and kill his mother.
 
    His mother came to believe the school put its reputation above her son's well-being.
  
    "You can't protect the institution and forget about the students,'' she said.
 
    The Associated Press is not naming the children or parents in this story to protect the identities of potential sexual assault victims.
 
    An AP investigation has detailed how K-12 schools in the United States can fail to protect students in their care from sexual assault, sometimes minimizing or even covering up incidents.
 
    Holding those schools accountable takes fortitude and patience, according to lawyers who bring court cases against schools.
 
    Eddie Schmidt, an attorney in Nashville, Tennessee, said he often tries to talk families out of suing.
  
    "A lawsuit is very expensive, very uncertain and it takes a long time,'' Schmidt said.
 
    The Miami case resulted in one of the largest verdicts in student-on-student sexual abuse. Jeffrey Herman, the boy's lawyer, successfully argued that Florida's $200,000 cap on damages in lawsuits against schools did not apply because Downtown Miami Charter School is privately run.
 
    A jury awarded the family $5.25 million in 2014. The school appealed and, in 2015, reached a confidential settlement.
 
    Not all states have such caps. In California, there are no liability damage limits on cases brought against public schools.
 
    But other restrictions abound. Virginia and Georgia give school districts absolute immunity from state lawsuits. Families who sue in Illinois must show the school demonstrated willful and wanton misconduct, not just negligence.
 
    In Tennessee, someone suing a school has no right to a jury trial but must go before an elected judge, who might be reluctant to rule against the government, Schmidt said.
 
    When Schmidt represented two seventh-grade boys who said they were sexually assaulted at their rural Tennessee school, he sued in federal court under Title IX, which prohibits sex-based discrimination in federally funded programs.
 
    The U.S. Supreme Court ruled in 1999 that all public school districts can be held liable under Title IX. Victims of sexual assault or harassment must show that school officials with the power to act were deliberately indifferent to known sexual harassment, and that the harassment was so bad it effectively barred a student's access to an education.
 
    That means victims who might find it difficult to sue in state court can often seek justice in federal court, though that's not necessarily easier.
 
    Schmidt's Title IX action in Tennessee lasted years before ending in a $200,000 verdict.
 
    One advantage to suing in federal court is that it can remove a case from the community, where victims may be under pressure to stay silent.
 
    Attorney Terry Heiss spent more than four years representing a boy from rural Michigan who said he endured years of abuse that ultimately escalated to a high-school locker-room sexual assault.
 
    Although court records show the attacker eventually pleaded guilty to a misdemeanor, the family received phone threats and had to temporarily relocate, Heiss said. The trial took place at a federal courthouse located hours away, moving it out of the hostile community.
 
    Jurors returned an $800,000 verdict -- more than the $500,000 Heiss requested. A judge overturned the decision , citing a lack of evidence that the school acted with deliberate indifference, but the parties had already reached a confidential settlement that still stands.
 
    Heiss said the boy felt the fight was worth it, despite the challenges.
  
    "One of the things that kept him going -- he didn't want it to happen to someone else,'' Heiss said.
 
    That's often the main motivator to sue, said Adele Kimmel, who specializes in student abuse cases for the Washington, D.C., nonprofit law firm Public Justice.
 
    Settlement agreements can require anti-bullying training in addition to money -- or sometimes instead of it.
 
    In the Florida case, the mother said she hired a lawyer only after her 7-year-old son's suicide attempt.
 
    According to her lawsuit, an 11-year-old boy forced him to perform oral sex in a transport van. The mother said she reported it to the school, which promised to monitor the older boy. Later, he cornered the second-grader twice in a school bathroom, again forcing him to perform oral sex, the lawsuit said.
 
    In a videotaped deposition played at the 2014 trial, the boy described feeling the abuse "would happen again and again.'' He said the smell of a school bathroom still triggered painful memories, leaving him feeling "very nervous, very upset, very scared.''
 
    In its response to the lawsuit, the school said it took reasonable measures to keep the boys apart and wasn't notified of inappropriate interactions on school property.
 
    Ultimately, the little boy's mother said, his testimony gave him a sense of empowerment.
  
    "It seemed like he was vindicated simply by saying, 'This happened. It hurt me. I'm still here.''' (AP)