Discriminatory Firing

Numerous federal, state, and even local laws restrict an employer’s right to fire an employee for discriminatory reasons.

Federal fair employment laws protect employees against various forms of discrimination in the workplace. Thus, for example, you could run afoul of federal law if you fire an employee solely on the basis of race, color, religious preferences, gender, national origin, disabilities (including substance abuse problems), or age.
Every state has laws that make it unlawful for an employer to fire an employee under certain circumstances. Many states have discrimination laws that give employees protection similar to, or greater than, corresponding federal laws. For example, some states protect employees from discrimination based on sexual orientation or personal appearance.
Many fair employment laws provide exemptions for employers having some minimum number of employees. However, merely because you qualify for a law’s exemption does not mean that you're free to fire employees that the law was designed to protect without any risk of being sued. Courts can, effectively, extend the law to you under the "public policy" theory. The fact that a law protecting a certain class of employees was enacted generally indicates a public policy in favor of that protection.

If an employee’s alcohol or drug use caused an accident, endangered another employee, or resulted in excessive absence, you may be tempted to eliminate the problem by firing the employee. Federal and state laws that protect disabled employees from discrimination may apply to alcoholics or drug users. It may be unlawful to fire an employee for substance abuse unless you take steps to reasonably accommodate the employee’s problem and give him or her a reasonable chance for rehabilitation. Should this happen, consult with a qualified employment lawyer before taking action.