In the case of Chevron U.S.A. Inc. v. Mario Echazabal, the Supreme Court ruled in favor of Chevron in 2001, upholding an employer's right to refuse employment if it could potentially harm the employee due to a pre-existing health condition. Echazabal had worked for contractors at a Chevron refinery for many years and applied directly to work for Chevron twice but was denied both times because he had Hepatitis C, which could be worsened by exposure to toxins at the refinery. The court found that under the Americans with Disabilities Act (ADA), an employer can reject a disabled applicant if it is determined that they would pose a "direct threat" to their own health or safety on performing essential job functions even though this interpretation goes beyond what Congress explicitly stated in ADA about threats only being applicable when risk is posed towards others.

In the dissenting opinion for Chevron U.S.A. Inc. v. Mario Echazabal, Justice Scalia argued that the Americans with Disabilities Act (ADA) does not allow an employer to refuse employment based on potential harm to the employee's own health due to workplace conditions, unless such harm would also endanger others in the workplace or affect job performance. He contended that Congress did not intend for employers to act as paternalistic guardians of their employees' well-being by making decisions about what level of risk is acceptable for them personally. Instead, he believed it should be up to individuals themselves and their doctors whether they wish to accept a job that may pose certain risks given their disability or medical condition.