You remember those ads from the 90s that would say, "It's 1:00 a.m., do you know where your children are?" Change that to 1:00 p.m. because, apparently, twenty years later, schools still haven't figured out how to not hire sex offenders. Yes, schools, the one place away from home where parents feel their kids will be safe, even if not learning anything. This is not an isolated problem. According to an editorial in the Seattle Times, "The number of students who are victims of sexual misconduct by a school employee between their kindergarten and 12th-grade school years is estimated by federal officials as in the millions. Much of the sexual abuse goes unreported."
Per the editorial, the Government Accountability Office (GAO) recently determined that school districts enable misconduct by not performing criminal background checks, performing inadequate screening, and ignoring red flags (e.g., applicant leaves criminal history question blank... oh well). The GAO attributed these failures to district officials not wanting to spend the time and money to perform extensive background checks on new applicants.
Another potential cause identified is that the offender's prior district is often reluctant to report misconduct out of fear of lawsuits. Some even provide glowing recommendations. If district officials do this out of fear of lawsuits, they need to reeducate themselves.
First, one cannot be liable for defamation for telling the truth about misconduct. Even in the event where a prior employer mistakenly communicates inaccurate details about misconduct, the former employer is typically protected by a qualified privilege due to their common interest, as well as the more general public interest. The end result is that the potential employee has to prove negligence, if not actual malice, on the part of the former employer, in making inaccurate statements. (See caveat below).
Given the small legal risk compared to the immense public interest, one would hope school districts could find the time and money to, at the very least, afford students the opportunity to not be harmed where they are supposed to be learning.
Amendment: Thanks to The Amateur Law Professor Justin Walsh for keeping up with case law and keeping me on my toes. He rightly points out that Bellevue John Does vs. Bellevue School District establishes privacy rights for teachers who are the subject of unsubstantiated or patently false accusations. Information related to such instances must not be disclosed.
I should emphasize that the short paragraph above about defamation is an oversimplification of two hundred years of case law. My point is that defamation or similar torts, such as public disclosure of private facts, are generally not in play when school districts communicate regarding instances of actual misconduct.