DUI Criminal Defence in Spain 2025: Alcohol, Breathalyzer & Rights

In Spain, drunk driving becomes a criminal offense when the blood alcohol level exceeds 0.60 mg/L in exhaled air (0.25 mg/L for professional drivers and novice drivers in their first 2 years). Below these thresholds, the offense is merely administrative. Understanding this boundary — and how to challenge breathalyzer evidence — is the foundation of DUI criminal defense. The margin between an administrative fine and a criminal conviction can come down to a single decimal in the reading, and to whether the test that produced it was correctly administered.

The Criminal Threshold

Art. 379.2 CP establishes two criminal categories: driving with a blood alcohol concentration exceeding 0.60 mg/L (per se offense, no need to prove impairment), and driving under the influence of alcohol or drugs with any concentration if impairment is demonstrated behaviorally. The practical result: even with alcohol below the threshold, if impaired driving is proved, criminal liability can arise.

What Happens After a Positive Test

The procedure normally starts with a roadside screening test. If it is positive, the driver is taken to perform an evidential test on a different device, with a second measurement after a waiting interval, and must be informed of their rights — including the possibility of requesting a blood analysis to contrast the result. Everything is documented in the police report, which becomes the backbone of the case. DUI cases are usually channelled through fast-track proceedings, which means the hearing can take place within days of the arrest: the window to prepare a defense is short, and decisions about accepting or contesting the charge often have to be made very early.

How to Challenge Breathalyzer Evidence

Spanish case law has established strict procedural requirements for breathalyzer evidence. Challenge grounds include: failure to offer the suspect a second test with a different device; failure to wait 10 minutes between tests; device not calibrated within required timeframe; administration not witnessed by two officers; failure to properly inform the suspect of their rights. Any single procedural defect can render the evidence inadmissible.

In practice, the defense requests the calibration and maintenance certificates of the device and the complete record of how the tests were administered. If the breathalyzer reading falls, the per se offense usually collapses with it, and the prosecution is left having to prove actual impairment through other evidence — essentially the officers' description of the driving and of the driver's condition, which is far easier to contest.

Defense Options and Outcomes

Possible outcomes in DUI criminal cases range from full acquittal (procedural defect or insufficiency of evidence) to conformidad (plea agreement reducing penalty), to conviction. Key mitigation factors: no prior criminal record, cooperation with authorities, immediate cessation of driving, and voluntary payment of any civil liability.

These factors do not erase the offense, but they shape both the penalty actually imposed and the realistic objectives of the defense: for a first-time offender, the practical goal is usually to limit the consequences as far as possible and protect their ability to keep working.

The Plea Agreement in Practice

Most DUI cases are resolved quickly, and the conformidad deserves a considered decision rather than an automatic yes. Accepting it means accepting the facts and the penalty proposed by the prosecution in exchange for a reduction; refusing it makes sense when the breathalyzer evidence carries procedural defects worth fighting. The right choice depends entirely on the strength of the evidence in the specific case. A conviction also creates a criminal record, which will weigh on any future proceedings — one more factor on the scale. That is why reviewing the file with a specialist before the hearing, even in an apparently simple case, is never wasted time.