Legal Question in Employment Law in California

California courts have generally permitted employers to require employees to submit to a drug test upon a reasonable suspicion of illegal drug use at or during work. There are not enough facts to answer your specific question. The test used is whether the employee has a reasonable expectation of privacy under the entirety of circumstances. Among the facts to be considered, are the employer's policies and procedures, any documents signed or disseminated, the nature of the job performed, public policy of preventing children from being exposed to drugs, your union's position on the matter, the extent of any intrusion, the credibility of the witness, and many other factors. My guess...being you work for a school district, the test can be justified.