Can You Be Denied Employment for a False Positive?

A false-positive result on a drug test may be cause for denial or termination of employment.
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Employers have the right to deny employment to individuals based on the results of a drug or polygraph test. However, sometimes these tests can return a false positive. Unless you can prove without a doubt that the test is incorrect, an employer can and likely will deny you a job.

False-Positive Results

Many employers require pre-employment screening, including drug or polygraph tests. Others mandate employees take periodic drug tests to maintain employment or be considered for promotions. A false-positive result is one that indicates the employee (or prospective employee) has an illegal substance in his body or lied during a polygraph test. Drug tests can yield false-positive results in many ways. Laboratories may be careless with specimens, and legal substances can cause false-positive indicators. For instance, Ibuprofen, shampoos or lotions that contain hemp and some ulcer drugs may cause a test to show positive for marijuana usage. Over-the-counter products containing ephedrine or phenyproplanolamine (often contained in diet pills or nasal sprays) may produce a result indicating amphetamine use. Also, consuming poppy seed muffins or dressing prior to a drug test may cause the test to come back with results indicating opiate use. A polygraph test may result in a false-positive verdict because of administrator error, extreme nervousness or faulty equipment.


There is no federal law that requires the majority of employers to test employees for drugs. The Drug-Free Workplace Act of 1998 does not indicate that all employers must employ drug testing in pre-employment screening or as conditions of continued employment. However, many states or municipalities do require some level of testing for certain industries or positions. Drug testing must be negotiated into union contracts in order to be legal. Otherwise, employers are able to decide for themselves if they want to test employees for controlled substances. Polygraph tests are certainly not required, either.

Employer's Prerogative

Many employers have a zero-tolerance policy and refuse to hear excuses or arguments about false-positive results. They consider drug testing to be essential for safety and performance in the workplace, and they may be concerned that employees will have illegal substances on them when they come to work. However, some employers take into consideration arguments that employees or candidates make about reasons their results came back incorrectly and may give some candidates the chance to retake tests.

Legal Help

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Anyone who receives a false-positive drug or polygraph test result may seek legal help from an employment lawyer. However, false-positive results are often difficult to prove and expensive to defend against. The best course of action is to state your case and ask to take the test again. If you really want the job and are certain the test was in error, you might even volunteer to pay for the second test.

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