In order to know where to start, it is important to understand that employment law consist of both federal law and state law. An employer is responsible for complying with both sets of laws because there are differences.
According to federal law, an employer cannot discriminate against you in the workplace based on: age, disability, equal pay/compensation, genetic information, harassment, national origin, pregnancy, race/color, religion, retaliation, sex, and/or sexual harassment.
The federal law only applies to employers with 15 or more employees working 20 or more weeks a year. The time limit to file an employment discrimination claim under federal law also varies based on the type of discrimination. For example, if you are claiming race discrimination, you must file a claim with the Equal Employment Opportunity Commission ("EEOC") within 300 days from the date you were discriminated. If you are claiming age discrimination then you have 180 days to file a claim with the EEOC.
States can create their own sets of law to provide additional protection for employees. Under the Minnesota Human Rights Act ("MHRA"), in addition to what is prohibited under the federal law, an employer also cannot discriminate against you on the basis of: public assistance, familial status, and/or sexual orientation.
Unlike the federal law, the MHRA applies to all employers in Minnesota, regardless of the number of employees there are. In addition, regardless of the type of discrimination, you have one year to file a complaint with the Minnesota Department of Human Rights ("MDHR").
If you think you have a claim that can be brought under the federal and state law, then you can choose to file your complaint with either the EEOC or the MDHR. If your claim involves public assistance discrimination then your only option is to file a complaint with the MDHR (since public assistance discrimination is not recognized under federal law). The EEOC and MDHR are responsible for investigating the claim. You cannot sue an employer directly in court unless you obtain a "right to sue" letter from the EEOC or MDHR.