State laws allow employers to test applicants for drugs. As a rule, an employer is allowed to take a drug test if the applicant is warned about such a possibility with advanced notice or it's stated in the job application as a part of the screening process. All tests are required to be administered by a state-certified laboratory. Additionally, all applicants to the position must be tested similarly; no discrimination is permitted.
Drug testing is usually required for safety-sensitive industries like transportation, safety, defense, and aviation. While private employees are not obligated to take a drug test, many federal employees are, including national security, law enforcement officers, employees with duties to protect property, life, and health.