I had a teacher try and pull that shit.

I would try to shake her hand every time I turned in a paper (Makes it legally binding)
Kept proof of every assigned paper I turned in.
Asked for a rubric for every assignment. If she did not have one, I would draft one and have her confirm by shaking hands. (She said I did not do the assignments correctly on several occasions)
I would cite the school manual on policies she did not follow.
I did countless more things to make her life difficult, for making mine.

I could and did threaten legal action for the shit she tried to pull on me. I was an asshole to secure my 4.5 GPA because that bitch hated me.