Question: What is at "at will" employment?
Answer: Simply put, at-will employment means an employer can fire an employee at any time for good, bad or no reason without incurring legal liability. Likewise, an employee has the freedom to quit their job at any time for any reason. In Arizona, unless an employee has a written contract promising employment for a certain period of time it is likely the employee and employer have an at-will employment relationship.
Examples of a "bad" but legal reason might include personality conflicts, a disagreement about sports, or that your employer doesn't like that you dyed your hair blue. The law does not provide protection where employers make employment decisions with "bad" (silly, ridiculous, illogical or arbitrary) motivations.
However, there is one very important exception -- employers cannot fire an at-will employee for unlawful reasons, such as retaliation or illegal discrimination. As a result, often when an employer terminates an employee for a "bad" (silly, ridiculous, illogical or arbitrary) reason, and the employee has engaged in protected conduct, or is a member of a protected class (race, religion, sex, etc.), there is then a case to be made that the employer's stated reason was not legitimate and was "pretext" for an unlawful termination (i.e a termination with retaliatory or discriminatory motive related to legally protected conduct or status.)