Challenging a drug blood test: substance, concentration and context

What was measured and which document records this?

The police describe drug checks in traffic with an indicative saliva test and possible blood tests. The initial test and the laboratory report do not have the same function. Therefore, ask whether the letter received concerns a selection result, notification or final research report. The body of a police document can also summarize a laboratory result. For targeted control, the original report with relevant appendices is important. A photo of a single number may omit its units and limitations. (police describe drug control in traffic)

Note which substance or measurable compound is mentioned and for which sample. The NFI information sheet on drugs in traffic provides a general background on common substances and effects. That background is not an individual conclusion about your research. The concrete result must be read within the method used and the legal provision. A name that resembles a substance in ordinary language should not be equated without explanation with any other chemical compound or with a certain actual degree of influence.

Check the trace identification number and timeline

The sample must be reliably linked to the correct collection and person. Compare the trace identification number in notification, official report and report. Record collection date, receipt at the laboratory and examination dates if stated. A deviation can be an administrative problem, but can also require targeted investigation. Do not immediately determine that a sample has been mixed up without examining the pieces. The specific link should be clarified, not replaced by a general suspicion against the entire laboratory.

Create a timeline from the designated driving time to collection and notification. Keep the documents and mention where a time is only a personal memory. Some procedural regulations focus on certain steps or deadlines; these may not be calculated the same for each component without checking. Have the lawyer apply the applicable version of the Alcohol, Drugs and Medicines in Traffic Decree to the specific course of events. An old example of a different research method can lead to an incorrect term question. (Decree on alcohol, drugs and medicines in traffic)

A concentration only becomes understandable with the correct scale

For example, a laboratory can report a concentration per liter of blood. Microgram and milligram are different units. Overwriting a number without units can therefore cause a major error. Also check whether the comparison is about the same substance and measurable compound. An internet overview for urine or saliva is not an obvious benchmark for a blood report. An expert can explain the report without a client having to make a complicated conversion themselves.

In the event of a dispute, it is useful to formulate the question precisely: is the value misread, is the reported substance unclear or is there doubt about the calculation? These questions do not require the same research. Moreover, a technical uncertainty in reporting does not automatically mean that the legal limit must be increased at your discretion. Ask what the laboratory actually reported and how it should be used under the applicable rules. A reassuring or alarming loose comparison is insufficient for this.

A fictional report with three annotations

Take a completely fictitious report in which sample XYZ states: THC 2.0 micrograms per liter and amphetamine 30 micrograms per liter. The first annotation reads: check identity and collection time at XYZ. The second is: read both reported substances, not just the first. The third is: determine which legal comparison applies to single or combined use. This is a reading example with invented values, not a representation of a real research report and not personal advice about criminality.

The example shows why the thought that THC is below the known single limit does not decide the entire assessment. The Decree also contains rules for combinations and measurable substances. Selecting one line of a report may miss the relevant legal context. Have the lawyer discuss the values ​​and current standard with an expert when interpretation is necessary. It is not about convincing yourself that a chosen number is favorable, but about verifiably applying the correct metric to the entire report. (Decision)

Read together which remedies have been researched

The NFI described in a publication of April 2026 that the blood analysis shows substances and concentrations and that single and combined use may differ. It must be clear for your own case which substances have actually been found and which legal regulations are applied to them. A reference to multiple substances in an initial suspicion is not necessarily the same conclusion as in the laboratory report. So check the original results and the actual accusation. (an April 2026 publication)

The ministerial regulation contains further implementation and reporting rules. Do not make your own sum of various substances as if every combination forms one simple total. Some legal equations have specific rules that require expert explanation. Alcohol or medication may also give rise to a different analysis, depending on the specific legal provision. A blanket statement that it was only a small amount of each drug does not answer that question. The report should be read in its entirety and with the appropriate standard.

A measured substance and driving skills are different questions

The NFI professional appendix on toxicological research describes research into exposure to substances and possible effects. That distinction is relevant for the conversation with a lawyer. Some traffic regulations work with legally designated limit values; a statement that you felt alert does not automatically eliminate that norm. Other questions about influence or functioning may require specialist interpretation. Therefore, it should be determined which provision is being criticized before general information about the duration of effect is used as a legal answer.

Old consumption, tolerance or prescribed medication must be discussed specifically. A prescription may be relevant to the assessment, but is not a general permission to drive under any influence. Avoid self-diagnosis based on a forum or general table. Note which resources were actually used, when and under what regulations, as far as is reliably known. Give that information to the lawyer and, if necessary, an expert. Do not post-fill uncertain quantities to fit an expected result.

Use the correct route before the opportunity expires

The Decree contains its own regulations for counter-examination after blood tests, including provision of a sample and requirements regarding application and payment. Check the notice immediately. The term and prescribed route should not be confused with a general objection to the criminal case. An email in which you say that the result is incorrect does not automatically constitute a valid counter-investigation. Ask the lawyer what actions are now required and how receipt or payment can be confirmed.

A self-administered test weeks later examines a different point in time and is therefore not the same control of the original sample. A GP statement about daily functioning also does not replace laboratory counter-examination. That does not mean that such information is never relevant; its meaning must be placed with the right question. The most urgent preparation is to keep the original notification and discuss your own response options immediately. Do not wait until the court hearing to explore the possibility of a counter-investigation for the first time.

A deviation must be linked to a concrete standard

Procedural control includes collection, identification, shipping, analysis and notification. Not every difference has the same legal effect. A misspelled name while the sample is otherwise unambiguously identifiable may require a different assessment than an unexplained mismatch of identification numbers. Let the lawyer determine which regulation applies and which facts are in the file. A list of all possible errors in each blood test is less helpful than a specific question about your own documents.

Also distinguish between technical reliability and a legal consequence of a violated standard. An expert can explain the method or sample data; the judge assesses the use of evidence in the criminal case. The Road Traffic Act and implementing rules must be applied in concrete terms. A procedural error does not automatically lead to an acquittal, nor does a technically plausible outcome make any guarantee irrelevant. The connection between norm, event and interest must be made visible in the defense.

An annotated report card for attorney and expert

Write comments on a separate copy and keep the original document unchanged. Include the exact location for each question. An advisor must be able to quickly see whether it concerns identity, concentration, standard or process route. Do not share results without accompanying context if this assumes a different sample or research moment. The map makes specialist consultation more targeted; it is not a substitute for the full report or the formal request for counter-investigation.

• Identity: person, trace identification number and link to the collection.
• Time: driving moment, collection, receipt, examination and notification.
• Substance: exact name, measurable compound and substances tested or not detected.
• Value: concentration, reporting unit and any explanation.
• Standard: legal provision used and relevant single or combination question.
• Check: concrete deviation, missing piece and appropriate expert question.
• Response: counter investigation, payment requirements, deadline and other ongoing procedures.

The same result can appear in more than one trajectory

A criminal case and a CBR trial have different goals and rules. A defense against the blood result in the criminal case does not automatically change a separate CBR decision. Therefore, keep all letters and record the term and requested response for each process. A decision about whether to retain the driver's license for longer may also be a personal question. It would be incorrect to give the impression that one counter-investigation automatically suspends all proceedings or forces them to the same outcome.

Our conclusion: a drug result is easier to assess when the technical data and the legal standard are separately clear and then carefully connected. Use the guide on combination use for that topic and have your own report read in time. Good advice starts with the concrete documents, not based on your own driving feeling. The map provides direction for research without promising a measurement error, acquittal or restoration of the driver's license in advance.