Falsely accused of providing project code to others in a class
There are a couple of things to realize. Many departments run assignments through plagiarism detection software. The software typically reports a "similarity index" which needs to be interpreted by a human. The exact process varies from department to department (and sometimes even between professors/TAs). It could very well be that any assignment with a similarity greater than X is automatically forwarded on to the academic misconduct committee. It could be the professor looks at the assignment and decides the similarity is great enough for further investigation.

The key is that investigations are not accusations of misconducted. The accusation happens after the investigation and at that point you can appeal. Every department I know of has an appeals process and none allow an appeal prior to the investigation.

Back to your case, the investigation will have two parts, that will likely be carried out together. The first is to determine if the current student cheated. The second will be to determine if you violated any polices in terms of helping the student.


  apart from saying that we did not provide the code, we do not have any ways to show that we are innocent (in fact now I think the procedure is very unfair to people like us)


While technically correct, there is the question of if the student obtained a copy of your code, how did they do it. My academic misconduct polices I am aware of require you to knowingly share past assignments with the intent of allowing the other student to cheat. Generally showing someone your past assignment, or looking at someone elses past assignment, is not cheating. Saying "here are my past assignments you can copy them if you want" is cheating. Saying "here are my past assignments make sure you only use them to learn and that you do not copy them" is not cheating.

If the student had access to your computer, or GIT hub account, or email, or notes, or ... but you didn't tell them they could look at your notes, you are probably in the clear. Knowing this would help the investigation. Maybe the current student is friends with the past TA. The key is to tell the investigation everything you know. You will also want to make sure the student tells the investigation how they got your past assignment.