Teacher's ability to reprimand a student for cheating on a test. DETAILS INSIDE.?

OK, the cl is high school physics. I took my physics midterm today, and my teacher accused me on cheating on it only because i got a 100% and finished it in 30 minutes. My fellow clmates took up to 2 hours and didnt make such a high grade. I am top of my cl, and have absolutely no trouble in physics. I have A's in all other physics ignments. The teacher called my parents, alerted administration, and is making me retake the test. I honestly did not cheat, i just need to know whether she has the authority to make me retake a test based purely off of her suspicion; there was no other evidence that i cheated, other than i finished much sooner then my clmates and made a 100 A. I don't really mind retaking it, but i think this is just a principle matter