A 4 panel drug test screens for four substance groups instead of five, and in most cases the missing one is cannabis. That is not an accident of laboratory design: it is the direct result of state cannabis law, and it is why a panel that barely existed as a commercial product a decade ago is now routinely ordered. This page explains what is on it, and the legal reasoning that made it popular.
What is usually on it
The common configuration is amphetamines, cocaine metabolites, opiates and phencyclidine: the federal five with cannabinoids removed. Some laboratories sell a different four, and as with every panel number the only reliable specification is the analyte list and the cutoff levels rather than the name. If a provider quotes you a 4 panel without telling you which four, that is the question to ask before you compare it with anybody else's.
Why employers drop the cannabis screen
A growing number of states restrict what an employer may do about a positive cannabis result for off-duty use, and several prohibit adverse action on the basis of a positive test alone for most roles. In those states a cannabis result creates a compliance problem rather than useful information: you have learned something you may not lawfully act on, and you now hold it in a personnel file. Removing the analyte is the cleaner answer, which is why the 4 panel became a standard product. Safety-sensitive and federally regulated roles are the exception and are usually carved out of those state protections.
Where it does not apply
None of this touches Department of Transportation testing. Safety-sensitive employees covered by 49 CFR Part 40 are tested on the federally specified panel including cannabinoids, at federally set cutoff levels, regardless of the law of the state they work in. Cannabis remains a Schedule I controlled substance federally, and the Department has been explicit that state legalisation does not change a regulated employee's testing obligations. An employer with both regulated and unregulated staff will often run two different panels for that reason.
Choosing a panel at all
The useful question is not how many substances you can screen for but what you would do with each result. A panel that reaches prescription medications needs Medical Review Officer capacity behind it. A panel that reaches cannabis needs a policy that survives your state's law. A panel narrower than your policy leaves you unable to enforce it. Decide the policy first and buy the panel that matches, rather than buying the broadest panel available and working out the policy afterwards.
Questions people ask about 4 panel drug test
What does a 4 panel drug test screen for?
Most commonly amphetamines, cocaine, opiates and PCP, which is the federal five without cannabinoids. Laboratories vary, so ask for the analyte list and cutoff levels rather than relying on the panel number.
Why would an employer not test for cannabis?
Because in a growing number of states an employer may not take adverse action over a positive cannabis result for lawful off-duty use in most roles. Screening for something you cannot act on creates a record without a decision behind it.
Can I use a 4 panel for DOT-regulated employees?
No. Regulated testing follows 49 CFR Part 40 and includes cannabinoids at federally set cutoff levels irrespective of state law.
Is a 4 panel cheaper than a 10 panel?
Usually somewhat, but the difference between panels is small next to the collection fee and any Medical Review Officer review. Panel choice should be driven by your policy rather than by the price difference.