My university is sanctioning me for arguing with another student in class, disrupting the classroom. How can I have my side of the story heard?

Although the expectation is that a student is at their college university to, of course, learn and to engage in discourse regarding a subject or issue, even if the subject issue is, of course, controversial. It's nature of academic freedom and academic expression that people may not agree with one another. Unfortunately, schools can be too quick to try to stifle such discourse and accuse a student of some misconduct related to say their beliefs or ideas or whatever may have been exchanged and even a class discussion.

You can't depend on the school to do the right thing. Just the fact that such an allegation would be made is obviously incredibly troubling. Witnesses that would speak to the fact that there was nothing improper that took place could be a potential benefit. You cannot fundamentally depend on the school to do the right thing, so before you engage with the school in any capacity, you need to take the necessary precautions.

You can present your side of the story, it will take the necessary defense, like as noted witnesses, if there's some possible transcription, even of the court class discussion, for example, if it was done online, like chats. Chats are sometimes an aspect of a class discussion, especially with online learning.

Taking the necessary precautions, and having an experienced academic misconduct attorney advisor in your corner will help best protect your rights and interest. They can also help you best understand and navigate the process. They should be involved as early as possible in a disciplinary case of that nature.