Can a job offer be rescinded if a background check is taking too long?

Absolutely. An employer can terminate an employee for any reason or even no reasons as long as it is not an unlawful reason. The same is true about extending and withdrawing job offers. There is nothing unlawful about deciding that it is taking too long for a final decision to be made. In fact, a good case could be made that such a motivation is a legitimate business decision. Good luck to you.

The law provides far less protection than most people assume. In general, employers--even public employers--can terminate employees who have not acquired tenure at any time for almost any non-discriminatory reason, absent a specific agreement to the contrary. There is no law against rescinding a job offer because the background check has taken so long, and indeed, rescission for such reason may serve a legitimate purpose if the school urgently needs someone to fill that place. http://www.johnphillipslaw.com

This matter was addressed in response to your previous post answered 2 days ago. The Dept of Justice report (Live Scan) reports the incident or event. It does not provide the critical circumstantial details about the offense. Your matter almost certainly got tagged for investigation because you have a conviction for a crime -- a crime that is always of concern to school employers. In California, infractions are crimes. See Penal Code section 16. You should talk with a criminal defense attorney about whether you qualify to have that infraction dismissed. That may help, but it is not a cure. The infraction will still be an issue for investigation by the potential employing school district. Inevitably the district you have applied to has made a request of the arresting agency and/or the Commission on Teacher Credentialing to forward the arrest and investigative reports so that the district can scrutinize and evaluate the underlying facts and circumstances. School districts, like State licensing agencies, are always focused on the underlying facts and circumstances, not the specific charge that was pleaded to. The investigation requested here can take as much as 6 months. The duration is not in the control of the requesting school district. There is no reliable timeline. Some districts will proceed with the appointment (hire) anyway on a provisional or conditional basis. Others will not move forward with appointment without the D of J issues resolved, but will utilize the intended candidate as a daily-hire substitute until that occurs. Other districts will simply leave the candidate hanging and unemployed while the background issues are completed per the standard and formal process. There is no cause of action that the candidate for employment can assert to claim exemption from the scrutiny of the background investigation and clearance. Even if the district erred in some way -- and there is nothing in your post that supports such inference -- the remedy of such error would not be that the district forfeits its vetting obligations and rights and an uncleared person is placed in a position of power and responsibility over children. Whether your district can bail on your candidacy if the D of J investigation pends longer than expected depends on the district's formal policy and whether there exists between you and the district any contractual provisions that constrain the district for any specified period of time on this basis. As stated before, you may want to consult with the union if the teacher positions in the district at issue are represented by a union. You don't yet qualify for union representation, but unions have a vast amount of institutional knowledge and memory and can often predict with accuracy what the district can and will do in many circumstances.