DUI Defence (Art. 379 CP): Breathalyser & Licence

Driving with a blood alcohol concentration above the legal limit is one of the most common offences in Spain and, when it crosses the threshold of Art. 379 of the Spanish Criminal Code, it stops being an administrative fine and becomes a criminal road-safety offence. As criminal lawyers specialised in DUI defence, in this article we explain the applicable thresholds, the real consequences and the most effective technical defence lines for challenging the breathalyser evidence.

Administrative vs. Criminal Thresholds

The distinction is decisive: it marks the difference between a traffic fine and a criminal record:

• Administrative track (General Traffic Regulation): Sanction from 0.25 mg/l of breath alcohol (0.5 g/l in blood). Fine and licence-points loss, no criminal record.
• Criminal track (Art. 379.2 CP): Offence from 0.60 mg/l of breath alcohol (1.2 g/l in blood), regardless of the actual driving.
• Driving under the influence (Art. 379.2 CP, first sentence): Even below 0.60 mg/l, an offence exists if it can be shown that alcohol was actually impairing the driving (zigzag, sudden braking, evident drowsiness).

Penalties and Real Consequences

Art. 379.2 CP punishes driving with criminal blood-alcohol levels with one or several of the following alternative penalties:

• Imprisonment of 3 to 6 months.
• Fine of 6 to 12 months (daily quotas between €2 and €400).
• Community service of 31 to 90 days.
• In all cases: deprivation of the right to drive motor vehicles for 1 to 4 years.

While imprisonment is usually suspended for first-time offenders, the licence deprivation is unavoidable and, if it exceeds 2 years, entails definitive loss of the licence: to drive again, you must take the exam again (Art. 47 CP).

Defence Lines: Challenging the Breathalyser

The breathalyser is a measuring instrument subject to a strict metrological control regime. Every procedural or technical defect is a defence avenue:

1. Expired or missing calibration. Each breathalyser must undergo periodic metrological inspections (annual or after a certain number of measurements). We always request the current certificate. Expired calibration nullifies measurement reliability.

2. Margin of error and tolerance zone. The metrological regulation recognises a margin of error of ±5% for evidential breathalysers. If the result is in the borderline zone (e.g. 0.62 mg/l), applying the margin places the driver below the criminal threshold. The defence invokes this as reasonable doubt.

3. Missing second mandatory measurement. The protocol requires two measurements separated by at least 10 minutes. If only one was done, or the interval was not respected, the evidence can be challenged.

4. Broken chain of custody. The denunciation report must identify the breathalyser by its serial number, record the exact time and the driver's signature. Formal errors (e.g. missing serial number) are frequent and useful.

5. Right to a blood counter-analysis. The driver may request a hospital blood test. If the Civil Guard did not inform him of this right, the evidence can be declared null due to a violation of the right to defence.

Refusing to Blow: More Serious Than the Positive

Refusing to take the breathalyser test is a standalone offence typified in Art. 383 CP, with penalties of imprisonment from 6 months to 1 year and licence deprivation of 1 to 4 years. The penalty is higher than that of Art. 379 CP, so refusing is never advisable: even if the result is positive, technical breathalyser defence is viable, while refusal turns the case into an almost certain conviction.

Alternatives to Trial: Plea Bargain and Substitution

Where the evidence is solid, mechanisms exist to minimise the impact:

• Plea bargain with one-third reduction in rapid trial (Art. 801 LECrim): reduces the penalty, avoids delay and allows negotiation of the exact licence-deprivation duration.
• Substitution of imprisonment with fine or community service: for sentences under 1 year for first-time offenders.
• Conditional suspension with road safety course: avoids prison entry in exchange for fulfilling conditions (Art. 80 CP).