Regarding pupil grades, the law states:

In the absence of clerical or mechanical mistake, fraud, bad faith, or incompetency on the part of the teacher, grades given by a teacher to each pupil shall be final and not subject to change by others. A board or superintendent shall not order a grade changed unless the teacher who gave the grade is given the opportunity to state orally or in writing, or both, the reasons the grade was given, and is, to the extent practicable, included in all discussions relating to the changing of the grade. (Ed. Code 49066)

No grade of a pupil in a physical education class shall be adversely affected due to the fact that the pupil does not wear standardized physical education apparel where circumstances beyond control of the pupil are involved. (Ed. Code 49066)

Boards must prescribe regulations requiring the evaluation of each pupil's achievements for each marking period, and requiring a conference with, or written report to parents when the pupil is in danger of failing a course. Unexcused absences equal to a number established by the board are grounds for failing grades. Parents must be given reasonable opportunity to explain the absences, and there must be a method for identifying in the pupil's record that the failing grade was assigned on the basis of unexcused absences. (Ed. Code 49067)

Withholding of Grades, Diploma, Transcripts

After affording due process, a school district may withhold the grades, diploma, and transcripts of a pupil responsible for willfully cutting, defacing or otherwise injuring district property until the pupil or the parent or guardian has paid for the damages, or completed a program of voluntary work if unable to pay. The district shall establish rules and regulations to implement this section.  (Ed. Code 48909)