Obama "Dear Collegue Letter"[0] policy threatened civil rights enforcement if schools disciplined more black and latino students than white students, assuming that disparities of the rate of discipline implied injustice, rather than matching up with disparities in the rate of behavior meriting punishment.

This was a disaster for schools; many students who would have been expelled were kept around disrupting teachers and students who had to bear their presence in classrooms, hallways, fighting each other, bullying students and teachers.

For about 5 years after this went into effect, my local school district that also allowed open enrollment around this time got an influx of students with bad behavior from previous schools enrolling and not being expelled for fighting and other repeated misbehavior and disruptions. There was huge wave of teachers and families leaving and enrolling in the rural school close by so both could actually do teaching and learning without interference. The schoolboard had a lot turnover until the now head got elected promising to drastically curtail open enrollment and apply whatever discipline policy they could get away with to revoke open enrollment rights from non-residents due to bad behavior.

Here is a great account [1] from a teacher about her experience in schools where discipline was severely limited and prevented expulsion of disruptive and violent students, and the obvious consequences to the degraded learning environment that resulted.

[0] https://www.ed.gov/sites/ed/files/about/offices/list/ocr/let...

[1] https://quillette.com/2019/02/10/public-educations-dirty-sec...