In states with "at will" employment laws, the boss doesn't always need a good reason -- or any reason at all -- for firing employees. There are exceptions in some states; an employer can be held liable for violating a contract, for example, or for acting in bad faith. In addition, if your employer fires someone for a discriminatory reason, then he might be breaking the law.
Federal Employment Law
The Fair Labor Standards Act and other statutes set out federal employment law. The FLSA, for example, sets the federal minimum wage. The feds also make the rules on overtime pay and work hours for minor employees. The Family and Medical Leave Act covers private-sector businesses with at least 50 employees. By the FMLA, you're entitled to 12 weeks of unpaid leave to deal with childbirth or a medical emergency in the family. If an employee refuses to work under conditions that violate these laws, a firing on those grounds would be a legal no-no.
By federal law, you can't discriminate in the workplace based on someone's race, color, creed, gender, national origin or religious affiliation. There are federal statutes governing sex-based pay discrimination, as well as discrimination against qualified disabled workers and employees 40 years of age and older. If you've been discriminated against and fired illegally, you can file a complaint with the Equal Employment Opportunity Commission, and in some cases proceed with a lawsuit in federal court.
Retaliation and Whistleblowing
Employers can't fire you for taking certain protected actions. An employee who files a workers' compensation claim, for example, may not be fired by an employer in retaliation. In addition, in most states an employer may not let you go for following established public policy, such as reporting for jury duty or refusing to commit perjury. There are also laws against firing an employee for filing bankruptcy, getting pregnant, or blowing the whistle on lawbreaking within the company.
The law enforces written contracts, and employers who fire contract employees without legal cause may be looking at a civil lawsuit. Most states also bar violations of an "implied contract," which can mean guidelines set out in an employee handbook, or an oral agreement on sales commissions or hourly wages. An employer may also be acting in bad faith -- and illegally -- when he violates or changes the terms of compensation, such as benefits or sick leave, and fires an employee who refuses to abide by these terms.
Founder/president of the innovative reference publisher The Archive LLC, Tom Streissguth has been a self-employed business owner, independent bookseller and freelance author in the school/library market. Holding a bachelor's degree from Yale, Streissguth has published more than 100 works of history, biography, current affairs and geography for young readers.