Drug Testing Best Practices for Employers
Ten compliance-focused best practices for building and maintaining a defensible workplace drug testing program — covering DOT and non-DOT requirements, collection procedures, MRO review, and more.
Scott Galing
President, Do It Right Screening — 30+ years of industry experience
Establish a Written Drug-Free Workplace Policy
Every employer drug testing program starts with a written policy. Your policy should clearly define which employees are subject to testing, what substances are tested for, what circumstances trigger testing (pre-employment, random, post-accident, reasonable suspicion, return-to-duty), and the consequences of a positive result or refusal. Distribute the policy to all employees and require signed acknowledgment. A policy that exists only in practice — but not on paper — provides no legal protection.
Understand the Difference Between DOT and Non-DOT Programs
DOT-regulated testing (governed by 49 CFR Part 40) has specific requirements for the testing panel, collection procedures, MRO review, and random testing rates that differ from non-DOT workplace testing. DOT tests must use a 5-panel urine test at a federally certified laboratory with chain of custody documentation. Non-DOT testing gives employers more flexibility but still requires consistency and documentation. Mixing up DOT and non-DOT procedures is a common compliance error.
Use Certified Laboratories and Maintain Chain of Custody
DOT-regulated testing must use SAMHSA-certified (HHS-certified) laboratories. For non-DOT testing, using a certified lab is still strongly recommended for defensibility. Equally important is chain of custody — the documented, unbroken record tracking the specimen from collection to the lab to the MRO. A broken chain of custody can invalidate a positive result, leaving you exposed and unable to take adverse action.
Require MRO Review of All Positive Results
A Medical Review Officer (MRO) is a licensed physician who reviews confirmed positive drug test results before they are reported to the employer. The MRO contacts the donor to determine if there is a legitimate medical explanation (such as a valid prescription) for a positive result. Without MRO review, you risk taking adverse action based on a result that has a lawful explanation. Under DOT rules, MRO review is mandatory.
Manage Your Random Testing Pool Correctly
Random testing is only legally defensible when it is truly random — every covered employee must have an equal and unpredictable chance of selection each time. Use a qualified Third Party Administrator (TPA) or software to manage your random pool. Maintain accurate pool membership records (adding new hires, removing terminated employees promptly). Under DOT rules, the minimum random testing rates are 50% for drugs and 10% for alcohol annually.
Train Supervisors on Reasonable Suspicion Procedures
Reasonable suspicion testing must be based on specific, contemporaneous, articulable observations — not hunches. Supervisors need documented training on recognizing the signs and symptoms of drug and alcohol impairment. Under DOT regulations, supervisors of CDL drivers must complete at least 60 minutes of alcohol awareness training and 60 minutes of drug awareness training before they can make a reasonable suspicion determination. Document the training.
Follow the Return-to-Duty Process After a Violation
An employee who tests positive or refuses a test cannot return to safety-sensitive duties until they have completed the return-to-duty process: evaluation by a qualified Substance Abuse Professional (SAP), completion of recommended treatment or education, a negative return-to-duty test, and follow-up testing as directed by the SAP (minimum 6 unannounced tests in the first 12 months). Under DOT rules, this process is strictly defined. Allowing an employee to return without completing it is a serious violation.
Apply Your Policy Consistently Across All Employees
Inconsistent enforcement of your drug testing policy is one of the fastest ways to create discrimination liability. If your policy requires post-accident testing after any workplace incident, test every covered employee involved — not just some of them. If a positive result leads to termination for one employee, the same standard should apply to all. Document every decision and the reasoning behind it.
Stay Current With State Marijuana Laws
As of 2026, marijuana remains a Schedule I controlled substance under federal law — but more than 40 states have legalized it in some form. Some states now restrict an employer's ability to take adverse action based solely on a positive marijuana result. Others provide explicit protections for off-duty use. Know the laws in every state where you employ workers, and update your policy accordingly. DOT-regulated employees remain subject to federal standards regardless of state law.
Partner With a Qualified Third Party Administrator (TPA)
Managing a compliant drug testing program in-house is complex — especially for DOT-regulated employers. A qualified TPA can manage your random pool, coordinate collections, track testing records, maintain MRO relationships, and flag compliance issues before they become violations. A good TPA acts as your compliance partner, not just a vendor. Make sure yours is experienced in your regulatory environment (DOT vs. non-DOT) and your industry.
Frequently Asked Questions
Can an employee refuse a drug test?
Under DOT regulations, a refusal to test is treated the same as a positive result — the employee is immediately removed from safety-sensitive duties and must complete the full return-to-duty process before returning to work. For non-DOT employees, the consequences depend on your policy, but most policies treat refusal as grounds for termination.
What is the difference between a 5-panel and 10-panel drug test?
A 5-panel test screens for marijuana, cocaine, opiates, amphetamines, and PCP — the standard DOT panel. A 10-panel test adds barbiturates, benzodiazepines, methadone, propoxyphene, and Quaaludes. Employers can also add expanded panels (synthetic opioids, alcohol, etc.) for non-DOT testing depending on the role and industry.
How often should employees be randomly tested?
Under DOT regulations, the minimum annual random testing rates are 50% for drugs and 10% for alcohol. For non-DOT programs, the frequency is set by your policy — common rates range from 25% to 50% of the covered workforce annually. Higher-risk industries or roles typically warrant higher rates.
Do we need a drug testing program if we are not DOT-regulated?
You are not legally required to have a drug testing program unless your industry or workforce is federally regulated (DOT, NRC, DOD, etc.). However, many employers implement voluntary programs to reduce workplace accidents, control workers' compensation costs, and maintain a safer work environment. Some states also offer incentive programs for drug-free workplace certification.
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