Pennsylvania is an "employment-at-will" state.  This means that unless there is an employment contract, an employee may be fired at any time, for any reason or for no reason at all.  The employer does not have to have "cause".

There are a few narrow exceptions to this rule.  Federal law prohibits discrimination in the workplace based on an employee's gender, disability, race, color, religion, national origin, age and/or pregnancy.  The Family and Medical Leave Act also protects those taking time off for family and/or medical reasons.  The Pennsylvania Human Relations Act, a Pennsylvania state law, makes it illegal to discriminate on those grounds, and also based on an employee's willingness to participate in an abortion or sterilization procedure. 

Unless the firing was due to one of these legally recognized forms of discrimination, the employee will generally have no valid basis to sue.  This is true even where the employee's work performance was outstanding. 

What's more, the limitations on an employer's general right to fire employees at will are narrow.  For instance, as discussed in The Axelrod Firm e-newsletter at http://www.fearlesswomennetwork.org/articles.php?action=15, the United States Supreme Court ruled in Gross v. FBL Financial Services, Inc. that an employer may fire employees on account of their age, so long as age is not the sole reason it does so.  In February of this year, in Noecker v. Reading Hospital, the court in the Eastern District of Pennsylvania ruled that an employer was legally entitled to fire an employee whose pregnancy made her unable to perform duties required of her job.  She had not been with her employer long enough to qualify for pregnancy leave under the Family and Medical Leave Act.  The law would otherwise have protected her.

While an employee may bring a wrongful termination suit, doing so requires proving the firing violated public policy.  That public policy must be found in the Constitution, regulations, legislation or case law.  Courts interpret this basis for bringing suit narrowly.  For instance, in Weaver v. Harpster, a Pennsylvania state appellate court, the Superior Court, considered a wrongful termination suit.  The woman who brought the action claimed she resigned due to sexual harassment.  She could not bring suit under the Pennsylvania Human Relations Act as she worked for a company with less than 4 employees, and the Act applies only to larger companies.  She claimed she should still be entitled to pursue a wrongful termination claim.  There is a clear public policy against sexual harassment, she reasoned.  However, the court ruled for her employer, reasoning that the law was specifically designed to keep smaller employers outside of its reach. 

In summary, employment discrimination is a narrow field.  Most firings are legal -- the law recognizes few as unlawful.