Thank you for trusting your question to JA today. I am a licensed attorney with over a decade of law practice and over 20 years of experience in the legal field. I’m happy to be of assistance.
In an "at will" position, a person can be terminated at any time, with or without cause. Retaliation is a very specific legal term in employment law and requires that you complain of a specific form of harassment. You have to complain of being harassed based on race, religion, gender, age, disability or recent FMLA (medical leave) use discrimination. Then any adverse employment action following that complaint can be considered retaliation under the law.
However, just making a complaint of generalized harassment to HR does not create any sort of statutory protections from retaliation. Only a very narrow few complaints (those I mentioned) obtain protections from retaliation.
So, unless that was the basis for his complaint, he'd have no particular rights to refuse to meet with his boss prior to the HR investigation completion.
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