Worrying about your employment with a drug arrest on your record is understandable. According to IN.gov, employers can fire employees at will, with some exceptions.
However, nothing is ever black and white regarding employment rights. For example, the Americans with Disabilities Act (ADA) has a provision for recovering drug abusers and alcoholics.
Under Title I of the ADA, if you have a history of substance abuse and went through rehabilitation, your employer cannot discriminate against you. This includes former drug users who are in the process of rehabilitation. The federal government considers certain drug addictions a disability if they cause substantial impairment. Casual drug use is not a protected status, though. So, if you have an arrest on your record but cannot demonstrate any rehabilitative treatment, you may not have protection under the ADA.
Limits to ADA protections
Current drug users have no protection under the ADA. Additionally, enrolling in a rehabilitation program after you break the company rules does not protect you from termination. The ADA explicitly states that employees cannot claim rehabilitation immediately after an arrest or failed drug test.
Sealed or restricted records
Indiana employers cannot ask if you have a sealed or restricted criminal record. You do not have to list any convictions under restricted access during the application process. If your company fires you after a background check, you might have an opportunity to file a civil suit.
Even though Indiana is a no-cause state, you still have federal and state protections. Drug arrests might count against your employment, but your employer does not have the right to fire you under every circumstance.