An employer’s freedom to select one applicant over another for a particular job may be constrained by the need to comply with various laws prohibiting discrimination on grounds such as race, gender, disability, age, union membership or non-membership, and so on. Unless an exemption applies, it is unlawful to refuse to hire a person because of such attributes. The laws that prohibit discrimination seek to promote the principle of equal opportunity by proscribing based on certain characteristics.