The ADA and its administrative regulations (29 C.F.R. 1630, July 16, 1991) introduced the concepts of direct threat and significant risk of substantial harm. These narrow the traditional right of an employer to exclude workers who might be injured or injure others. The following regulations must be combined with the requirements of Arline to determine the proper balance between employee rights and the duty to protect the employee and the public when developing a communicable disease policy:

Direct Threat means a significant risk of substantial harm to the health or safety of the individual or others that cannot be eliminated or reduced by reasonable accommodation. The determination that an individual poses a “direct threat” shall be based on an individualized assessment of the individual’s present ability to safely perform the essential functions of the job. This assessment shall be based on a reasonable medical judgment that relies on the most current medical knowledge and/ or on the best available objective evidence. In determining whether an individual would pose a direct threat, the factors to be considered include

Determining whether an individual poses a significant risk of substantial harm to others must be made on a case by case basis. The employer should identify the specific risk posed by the individual. For individuals with mental or emotional disabilities, the employer must identify the specific behavior on the part of the individual that would pose the direct threat. For individuals with physical disabilities, the employer must identify the aspect of the disability that would pose the direct threat. The employer should then consider the four factors listed in part 1630:

Such consideration must rely on objective, factual evidence—not on subjective perceptions, irrational fears, patronizing attitudes, or stereotypes— about the nature or effect of a particular disability, or of disability generally.… Relevant evidence may include input from the individual with a disability, the experience of the individual with a disability in previous similar positions, and opinions of medical doctors, rehabilitation counselors, or physical therapists who have expertise in the disability involved and/or direct knowledge of the individual with the disability.

An employer is also permitted to require that an individual not pose a direct threat of harm to his or her own safety or health. If performing the particular functions of a job would result in a high probability of substantial harm to the individual, the employer could reject or discharge the individual unless a reasonable accommodation that would not cause an undue hardship would avert the harm.

The assessment that there exists a high probability of substantial harm to the individual, like the assessment that there exists a high probability of substantial harm to others, must be strictly based on valid medical analyses and/or on other objective evidence. This determination must be based on individualized factual data, using the factors discussed above, rather than on stereotypic or patronizing assumptions and must consider potential reasonable accommodations. Generalized fears about risks from the employment environment, such as exacerbation of the disability caused by stress, cannot be used by an employer to disqualify an individual with a disability. (29 CFR1630, Appendix at 1630.2(r))