students of a particular race, as compared to students of other races, are disproportionately: sanctioned at higher rates; disciplined for specific offenses; subjected to longer sanctions or more severe penalties; removed from the regular school setting to an alternative school setting; or excluded from one or more educational programs or activities.
There's another factor that people usually don't take into consideration when they look at "disparate impact" whether it's in the criminal justice system or in school discipline.
If all you look at is a very basic report from a certain district which shows you acts committed and punishments issued and then you say
"hey look! this group is getting harsher punishment for the same act as compared to this other group!" you are failing to take into account this very important consideration. That consideration being the
specifics of the incident.
Two students can be tardy or disruptive and do so in different ways. Both might be logged identically, but the actual events which unfolded may have some important differences which resulted in different punishment. If Student A comes into class late by a few minutes and this is only their third time doing it, and when taken to task by the teacher for it they are contrite and agree to improve while Student B comes into class much later, when the class period is almost over, and then when taken to task by the teacher is belligerent and confrontational and tells the teacher to F off, and shows complete disrespect for the teacher's authority and the importance of attending class, these two students might both reach the kind of statistics the DOJ has to look at with only "tardiness" for information of the offense, accompanied by information on how they were punished, with nothing going into those specifics. Student B may also have had many more unpunished incidents before the teacher had enough.
So to sum up, how did this specific incident fit into the offender's larger pattern of behavior, how severe was the offense, and how did they react to being disciplined?
Certain groups are more bought into cultures which dictate that you flout the rules and disrespect authority figures as much as possible in order to gain and retain cred, and
this culture is the explanation for both the higher offense rate among those groups, as well as the more severe specifics which translate into worse punishments.
These record keeping systems almost never are detailed enough to reflect these specifics and even when they do include some of that information, people who are tallying things up to show "disparate impact" and who want to explain it by blaming the teachers/police/courts rather than the offenders (and Eric Holder's DOJ is much more of this bent than most previous DOJ's) are not known for their honesty in incorporating that data.