Unless you have a written contract with your employer establishing a set number of years for your employment (for example, you are a football coach with a five-year employment contract), you can be fired for a host of traditional and obvious reasons: incompetence, excessive absences, violating certain laws or company rules or sleeping or taking drugs on the job. And you can also be fired or laid off because of company downsizing due to a downturn in revenue, reexamination of the company's mission, a merger with another company or transferring work to a factory in a lower wage area. In most cases, an employer does not need to provide any notice before giving an employee walking papers.
Still, there are limits. Employers do not have the right to discriminate against you illegally or to violate labour laws, such as those controlling wages and hours. Most state discrimination laws are quite broad. In addition to protecting against the traditional forms of discrimination based on race, color, religion, national origin and age, many also protect against discrimination based on sexual orientation, physical and mental disability, marital status and receiving public funds. Separate state laws protect workers from being fired or demoted for taking advantage of laws protecting workers from discrimination and unsafe workplace practices. And there are a number of other more complex reasons that may make it illegal for an employer to fire you -- all boiling down to the fact that an employer must deal with you fairly and honestly.