Thank you for your question today, I look forward to assisting you. I bring nearly 20 years of legal experience in various disciplines.
It's not illegal to demote someone based on a single write up or, in fact, no write up at all, unless that person has a contract of employment specifically stating that the terms of their employment may not be altered without their consent.
Now, you've mentioned being a veteran and disabled, but those facts alone give you no protection from demotion or termination
. Only if you are alleging that one or both of those factors actually played some part in your demotion will it have any legal bearing.
If you believe that you are veteran status or disability was an actual basis for your demotion, you need to complain first to HR and then, if they do nothing, contact the EEOC
in your state to complain about discrimination
. It is important though to first start with the HR of your company, because it takes away a defense that might otherwise raise (that they didn't get a chance to cure the issue before you complained to the EEOC). Making the complaint to HR is a protected activity.