A positive drug test triggers a specific chain of events, and what happens next depends on the context: a workplace screening, a federal safety job, or a court-ordered test. In most cases, the result doesn’t become final immediately. It first goes through a verification process that includes a second, more precise lab test and a review by a medical professional. Only after that does it carry real consequences.
Your Result Goes Through Two Rounds of Testing
The first test your sample undergoes is called an immunoassay, a rapid screening that flags whether a substance might be present. This test is considered presumptive, not definitive. It can only identify a broad drug class and is known to cross-react with unrelated substances, producing false positives. Common culprits include certain allergy medications, poppy seeds, and some antidepressants.
If the initial screen comes back positive, the lab runs a second, more advanced test on the same sample using a technology called mass spectrometry. This confirmatory test identifies the specific drug and its byproducts at much lower detection limits, making false positives far less likely. A result is only reported as positive if it clears both rounds.
Each substance has a specific threshold it must exceed to count as positive. For a standard federal urine test, marijuana metabolites must reach 50 ng/mL on the initial screen and 15 ng/mL on confirmation. Cocaine metabolites require 150 ng/mL initially and 100 ng/mL to confirm. Fentanyl has the lowest cutoff at just 1 ng/mL for both rounds. Oral fluid tests, which are increasingly common, use different (generally lower) thresholds. These cutoffs mean trace or incidental exposure usually won’t trigger a positive result.
A Medical Review Officer Contacts You
Before your employer or any authority sees a confirmed positive, a Medical Review Officer (MRO) reviews the result. The MRO is a licensed physician whose job is to determine whether there’s a legitimate medical explanation for the positive test. They will contact you directly, usually by phone, and ask whether you have a valid prescription or any other medical reason for the substance detected.
If you have a prescription, the MRO doesn’t just take your word for it. They will call the pharmacy to verify the prescription is authentic and current, and they may also contact your prescribing doctor if anything seems questionable. Photos of a medication label alone are not accepted as proof. If the MRO confirms a legitimate prescription, the result is reported to your employer as negative, and you face no consequences.
If there’s no valid medical explanation, the MRO verifies the result as a confirmed positive and reports it.
You Can Request a Retest
When your sample was originally collected, it was divided into two vials: a primary specimen and a split specimen. If the MRO notifies you of a verified positive, you have 72 hours from that notification to request testing of the split specimen at a different laboratory. This is your right under federal testing rules, and the employer is required to honor the request.
Requesting a split specimen test does not pause the consequences. In federally regulated testing, your employer can still remove you from your position while the retest is pending. If the split specimen comes back negative or the result is inconsistent, the original positive is canceled.
What Happens at Work
The consequences of a verified positive depend heavily on your industry and your employer’s drug policy. There are two broad categories: federally regulated jobs and everything else.
Safety-Sensitive and DOT Jobs
If you work in a federally regulated, safety-sensitive role (trucking, aviation, rail, transit, pipeline, or maritime), the rules are strict and non-negotiable. Your employer must immediately remove you from safety-sensitive duties upon receiving the verified positive. They do not wait for the written report or the split specimen result.
To return to work, you must complete a formal return-to-duty process. This starts with an evaluation by a Substance Abuse Professional (SAP), who determines what education or treatment you need. After completing the recommended program, the SAP conducts a follow-up evaluation. Only then can you take a return-to-duty drug test, which must come back negative before you’re allowed back into your safety-sensitive role. Follow-up testing continues for at least 12 months after you return. For airline employees who hold medical certificates, the MRO is also required to notify the Federal Air Surgeon within two working days.
Private Sector Jobs
Outside of federally regulated industries, consequences vary by company and by state. Some employers have a zero-tolerance policy and will terminate you after a single positive result. Others offer employee assistance programs, a chance to complete treatment, or a probationary period with follow-up testing. Many employers place you on administrative leave while they determine next steps.
State laws play a significant role here. Some states, like Illinois, require that you be given the opportunity to contest the results. Others have specific notice requirements or mandate that employers follow their written drug policy consistently. Employers that apply testing procedures inconsistently across employees can face discrimination lawsuits. In most cases where courts have ruled against an employer, the key issue was that the company failed to engage in any dialogue with the employee before taking action.
What Happens in the Legal System
If you’re on probation or parole and fail a court-ordered drug test, the situation is more serious. A positive result is typically treated as a probation violation, and your probation officer will report it to the court. The court then schedules a violation hearing.
At that hearing, a judge generally has three options: continue your probation with no changes, add new conditions to your probation (such as mandatory treatment or more frequent testing) and potentially extend the probation period, or revoke your probation entirely. Revocation means you could be required to serve some or all of your original suspended sentence in jail. The outcome often depends on the substance involved, whether it’s your first violation, and whether you were already participating in treatment.
How to Protect Yourself
If you receive a positive result and believe it’s wrong, your strongest options are requesting the split specimen retest within the 72-hour window and providing full documentation of any prescriptions to the MRO. Keep pharmacy records, not just pill bottles, readily accessible.
If you’re in a workplace dispute over a positive result, pay attention to whether your employer followed their own written policy. Procedural errors, such as skipping the MRO review, failing to offer a retest, or not following chain-of-custody protocols during collection, can be grounds for challenging the result. Some states also allow you to get an independent retest at your own expense.
For court-ordered testing, honesty with your attorney before the hearing matters more than anything else. Judges tend to respond more favorably when a violation is paired with a clear plan for treatment rather than denial, especially for a first offense.