Employer’s motivation can be very difficult to prove because, in essence, you’re trying to prove somebody’s state of mind. The best way to prove employment discrimination is through direct evidence which is usually verbal or written statements that directly link adverse employment action taken against you to you being a member of one of protected categories. For example, if there is a memo that states that the boss does not like Hispanics and then you’re terminated.
Of course, employers are usually way too sophisticated to leave a paper trail of any discriminatory intent. In most cases, we rely on circumstantial evidence and we put together piece of the puzzle to paint a picture for the court and for the jury that suggests that an employee has been discriminated against.