https://www.ed.gov/laws-and-policy/civil-rights-laws/race-co...
The policy warned schools that racial disparities in punishments could trigger federal civil rights investigations under a "disparate impact" standard.
Ergo, presumably, if a school had a single purple student. And that purple student was punished for something. Then the entire school had to also be punished for the thing. To not fall afoul of the law. (Or maybe I'm just too autistic to have a nuanced take.)
(Trump rescinded it.)