No Negative Treatment
An employee is entitled to take time off for jury duty or for a court appearance as a witness as required by law if he or she gives the employer reasonable notice, and may not be discriminated against for doing so. (Labor Code § 230(a)-(b).)  An employee who is discharged or otherwise discriminated against for taking such time off is entitled to reinstatement and reimbursement for lost wages and benefits. (Labor Code § 230(e).) Willful refusal to rehire, promote, or “otherwise restore” an employee or former employee who has been determined eligible for rehire or promotion by a grievance procedure, arbitration, or hearing authorized by law, is actually a misdemeanor.  (Ibid.)
The California Education Code similarly protect teachers and students from any sort of discrimination or negative treatment.  (Education Code §§ 44037; 87036.)
Wage and Salary Practice
There is a big difference between how an employer must pay an employee who serves on jury duty or appears as a witness, dependent upon whether the employee is an exempt or non-exempt employee.  Specifically, employers are not required to pay nonexempt employees during jury or witness service leave. Because nonexempt employees must be paid only for hours worked, the employer is not required to pay the employee for the time spent on jury duty or in court as a witness.
However, employers must pay most exempt employees who are absent for less than a full workweek on jury or witness duty for the full week.  This is because most exempt employees are paid “on a salary basis” in order to be exempt from overtime. That means under federal law they must receive their full salary for any week in which they perform any work, without regard to the number of days or hours worked.  (29 CFR §541.602(a).)  Yet, according to California Division of Labor Standards Enforcement Policies and Interpretations Manual (“DLSE”) section 51.6.10, employers are permitted to prorate the amount of salary paid to an employee based upon an absence of an entire day or more of the workweek.  Thus, for example, if the employee misses two days of a 5-day workweek, the employer is permitted to reduce the salary for that week to 3/5 pay.  Please note that any work performed by the employee on a work day precludes such a reduction.  This includes reading emails, taking phone calls, or “being available”. The employee cannot just announce that he/she is “available” rather, there must be some indication from the employer that the employee will not be completely, duty-free.
An employee is not paid “on a salary basis” if the employer makes deductions from his or her “salary” for time spent on jury duty or in court as a witness, during any week in which the employee performs any work.  (29 CFR §541.602(b)(3).) Therefore, an employer that docks an exempt employee pay for time served on a jury or as a witness runs the risk of that employee being re-classified as non-exempt.  If they are so re-classified, the employer could be on the hook for unpaid overtime compensation for all overtime hours worked in a 2- or 3-year period.
The employer is permitted to offset any amount received by an exempt employee as fees for jury duty or serving as a witness.  (29 CFR §541.602(b)(3).)  That offset is appropriate and will not trigger re-classification or impose overtime compensation liability.
Unless otherwise provided in a collective bargaining agreement, an employee is entitled to use available vacation, personal leave, or compensatory time off to compensate for otherwise unpaid service as a juror or witness in a court proceeding.  (Labor Code § 230(g).)