Part of a federal law that prohibits discrimination on the basis of someone having a disability. Disability is determined on a case-by-case basis and does not include conditions such as substance abuse. This law applies to the whole employment cycle, from application through advancement and termination.
It protects qualified individuals with disabilities that might otherwise prevent them from rightful access to jobs and roles that they are capable of working in. As part of the equal employment opportunity commission, Americans with disabilities cannot be discriminated for any health conditions that may be prejudiced against.
Through protection and representation from this federal agency - people with disabilities are ensured that they retain their right to work. The ADA specifies some particular dispositions that will always be considered to be impairments - most notably physical disorders. Cancer, multiple sclerosis and some other serious impairments are not considered disabilities.
There are some mental impairments included on the list, however, these can vary. For example, depression and stress are only considered impairments if they result from a documented mental or physiological disorder.