General protections; what is adverse action
The Fair Work Act renders it unlawful for a person or corporation to take adverse action against another person for a prohibited reason. For example it is a breach of the general protections and thus unlawful for adverse action to be taken against a person because he or she has exercised a workplace right or where it is motivated by specifically nominated forms of discrimination.
What is adverse action?
Here is a brief passage from a case which explains it.
“The phrase “alters the position of the employee to the employee’s prejudice” in Item 1 of s.342(1) of the FW Act constitutes a broad additional category of adverse action which covers any adverse effect upon, or deterioration in, the advantages enjoyed by the employee prior to the conduct in question. A prejudicial alteration must be real and substantial, rather than merely possible or hypothetical, but may occur even though there is no loss or infringement of a legal right as such: Klein at  per Gordon J.”
Fair Work Ombudsman v NSW Motel Management Services Pty Ltd (2018) FCCA 1935 delivered 20 July 2018 per O’Sullivan J