In light of what you have added in the comments:
What my teacher did was assume that the reason that more
African-Americans were in jail was because of a flaw in the justice
system, not because of something else.
I would strongly disagree with the accepted answer and advise you to let it go. Given the current political climate in the United States, questioning whether the US judicial system systematically disadvantages African Americans is not a good idea and instead of changing your teacher's or your classmates minds you are more likely to get yourself reprimanded or (depending on what point exactly you're trying to argue) seriously damage relationships with your teachers or fellow students.
I will give you the benefit of the doubt and assume you'd prefer if your teacher had said something like:
"The main cause of higher incarceration rates of black Americans is poverty and marginalization due to centuries of systemic oppression".
I'm not going to go into whether or not that is true, i.e. to what extent this is a more important factor than judicial injustice (which definitely exists as well) because this is a complicated problem and research is not entirely conclusive.
In any case, because this is such a delicate issue, especially now, if you are not very careful with how you present your point you risk positioning yourself as someone who disagrees with the notion that certain ethnic groups are systemically and heavily disadvantaged (even if that is not your intention). I would argue that this risk is not worth the potential minor correction to your teachers arguments.
I can attest to this from personal experience since I grew up in Germany, where both history and politics classes are focused around the countries troubled past and its relationship with the present. Especially with the rise of far right political parties in recent years, more and more students might now question the status quo with respect to e.g. the treatment of minorities within Germany because radical viewpoints are becoming more normalized. As one can guess, these sort of discussions never end well, in the best case the students in question change their minds, in the worst they alienate themselves from their communities.
So in light of this, I think at most you should ask your teacher to privately clarify what he meant when he held his presentation and maybe ask him to add a bit more nuance to some points. I would very much advise you to not outright debate him or involve the rest of the class.