I just found out that someone who was hired after I was is making more money than I am. Is that legal?

Transcript:

Typically, wages are negotiated between employees and it can be okay for an employer to pay one employee more than another. Where we get concerned about that as labor employment lawyers, is if someone is being paid more because of a protective category like their age, their race, their sex, their gender. My first question would be who is that other person and why are they getting more pay? If it’s based on seniority, additional education or experience, then it’s probably okay. If there’s something else going on, then that would be something to inquire further.