The ADA does allow an employer to refuse to hire persons whose employment in the proposed job would pose a direct threat to others. This recognizes the existing rule that employers may choose to protect employees from harm and protect themselves from workers’ compensation claims. The primary difference under the ADA is a greatly strengthened presumption that the employee is fit for work.

Direct threat means a significant risk of substantial harm to the health or safety of 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 perform the essential functions of the job safely. 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 the following:

1. The duration of the risk;

2. The nature and severity of the potential harm;

3. The likelihood that the potential harm will occur; and

4. The imminence of the potential harm.

Most critically, the determination must be made on a case-by-case basis. Employers must be prepared to prove a “high probability, of substantial harm; a speculative or remote risk is insufficient.” For example, if the threat is due to a behavioral disorder, the employer must identify the specific behavior that would pose a threat and the likelihood of occurrence. If the behavior is quasi- voluntary, such as sexual assault, an assurance by the employee that he is reformed would probably defeat the employer’s attempt to prove him unfit. Compliance with the ADA provides no defense, however, if the employee assaults a customer. The injured customer may sue the employer for negligently hiring a known rapist. Although the ADA requires that accommodations be reasonable, it often seems to employers that the law itself is unreasonable.

Interestingly, there are only two U.S. Supreme Court decisions on the meaning of “direct threat” and both deal with communicable disease. The first arose under the Rehabilitation Act and involved a teacher who was infected with tuberculosis. [School Bd. of Nassau County, Fla. v. Arline, 480 U.S. 273 (1987).] The school district wanted to remove her from the classroom because it feared that the children would be infected. The teacher had an expert from the public health department who certified that she was not infectious at the time. The Court found that she did not pose a direct threat and could not be excluded from the workplace. However, the Court stated forcefully that if she became infectious to others, she would pose a direct threat and would have to be excluded from the workplace. (This case is discussed more fully later in this section.)

The second case is the dentist case discussed earlier in this section. The dentist refused to do dental work, including drilling, on an HIV–infected person in his office. The dentist claimed that he was concerned that he could not do adequate infection control in his office and offered to do the work at no extra charge at the hospital. (There was no discussion of whether there would be a charge by the hospital, but it is assumed there would be.) The patient refused and sued, alleging that the dentist violated the ADA. The dentist asserted the direct threat defense. He lost in the lower courts, but the U.S. Supreme Court ruled that he should be allowed to present evidence that HIV posed a threat to him or others unless he did the procedure at the hospital. This is an important precedent, although not necessarily the best facts. The case was remanded for trial and at the time of publication it was not determined if the jury accepted his defense.