– Cynthia Hsu is a contributor to FindLaw’s Free Enterprise blog. FindLaw is a Thomson Reuters publication. This article originally appeared here. –

As a small business owner, knowing some of the intricacies of wrongful termination law can be vital to preserving your business. Illegal firing of employees for reasons you may believe are justified might just land you in a costly wrongful termination lawsuit.

Most employees are “at will” in the U.S., meaning that they can be fired for whatever reason you want. Of course, that reason must be a legal reason.

So what are some of the common originators of wrongful termination suits? And, what should small business owners be aware of?

Discrimination: Discrimination is one of the biggest originators of wrongful termination suits. In 2008, the EEOC received about 95,402 workplace discrimination complaints. Firing an employee because of their race, gender, national origin, disability, religion and age are all illegal. So is firing someone who is in a “protected class,” such as a worker who is fired just because she is pregnant or recently gave birth. Some states have also included sexual orientation as a protected class.