The chain of custody – how a legally sound drug test is ensured
Chain of custody is the key to a result that holds up in the Swedish Labour Court. Step by step from sample collection to lab result to MRO review.
There is a saying in drug testing: "a result is never better than its chain of custody". If the chain is broken, the result will not hold up legally – no matter how sophisticated the lab is. This article goes through the chain step by step.
What is chain of custody?
The chain of custody is the documentation of the sample from the moment it is taken until the result is reported. Every hand that handles the sample must be recorded, and every time it changes hands this must be done with a signature and traceability.
Step 1: Identification
The person to be tested identifies themselves with photo ID. Their identity is documented on the sample collection form. This is more important than it sounds – if the identity can be questioned, the entire chain falls.
Step 2: Preparing the collection site
For urine samples: make sure the toilet has no water the tested person can access (coloured flushing liquid, sink turned off). For saliva samples: the employee must not have eaten, drunk or smoked for 10 minutes beforehand. For blood samples: standard medical hygiene.
Step 3: Sample collection under supervision
The sample is taken under direct supervision or with technical checks (temperature measurement for urine). The tested person can see the sample at all times – it is never handled out of sight.
Step 4: Sealing and labelling
Immediately after collection, the sample is sealed in the presence of the tested person. The tested person signs the seal. This is the heart of the chain: from this moment, the sample can be proven to be untouched.
Step 5: Transport
Sealed samples are sent to the lab using traceable transport. The recipient at the lab checks that the seal is intact and documents receipt.
Step 6: Confirmation analysis (GC-MS / LC-MS-MS)
Confirmation analysis is carried out using mass spectrometry (GC-MS or LC-MS-MS), methods that identify the substance specifically and quantitatively. This is the gold standard in drug testing and the level of analysis normally required for a legally sound basis in employment law matters. Provsvaret uses confirmation analysis only, without prior immunochemical screening, to ensure the highest possible specificity, reliability and legal robustness.
Step 7: MRO review
Before a positive result is reported to the employer, it goes to an MRO physician (Medical Review Officer). The MRO calls the tested person and asks about legitimate medical explanations (prescriptions, ADHD medication, codeine, etc.). Confirmed medical explanations lead to "negative"; unexplained results lead to "positive". Common cross-reactions that can cause false positives are well known.
Step 8: Reporting
The final result is reported digitally to the authorised recipient at the employer – not by email, not by phone, but in an encrypted portal with access control.
What happens if the chain is broken?
If the chain is broken (the seal is broken, the identity is questioned, documentation is missing), the result must be considered invalid and a new sample taken. Employers who nevertheless act on deficient samples risk both union disputes and losing in the Labour Court.
Provsvaret's process
Our process follows all eight steps above. We use accredited labs, MRO physicians with a specialism in toxicology, and a digital portal for encrypted reporting. Book a call and we will go through how we can upgrade your current process – or read more about our analyses for workplace testing.
Want to know more?
Contact us for personalized advice on drug testing and how we can help your organization.
