The Americans with Disabilities Act (ADA) views employer drug testing as legal if:

The ADA allows drug testing during the pre-employment process, as long as it is conducted consistently for all candidates. Testing for illegal drug use is not considered a medical examination under ADA.

Official Extract:

"Under the ADA, employers may conduct drug testing of applicants or employees, provided that tests are administered fairly and consistently and do not target individuals based on protected characteristics."

(Source: HRCI PHR Content Outline 2024–2025, Employee and Labor Relations Section, ADA Compliance and Drug Testing)