Americans with Disabilities Act of 1990
If a person with a disability thinks their employer has discriminated against them, they can make a complaint to the U.S. Equal Employment Opportunity Commission (EEOC).  The complaint has to be made within 180 days of when the discrimination happened.  If the EEOC thinks discrimination has happened, they will send a letter that tells the person with the disability that they have the right to sue (file a lawsuit against) their employer.  The person with the disability may then file a lawsuit in federal court.