This document discusses the validity and legality of pre-employment medical screening, specifically focusing on drug testing. It outlines the history of pre-employment physical exams and increasing concerns around privacy as medical data becomes digitized. Validity of drug screening tests is also examined, noting many legal prescribed medications can cause false positives for illicit drugs due to cross-reactivity. The document argues employers should use more specific confirmatory tests and consider factors like prescribed medications and food items that could impact screening results to avoid potential discrimination during hiring.