Mandatory breathalyzer after traffic accident; understand Contran rule and new proposal

Drivers involved in traffic accidents may be required by law to take tests, such as the breathalyzer, to identify the presence of alcohol or psychoactive substances in the body. The change in the Brazilian Traffic Code (CTB) is provided for in Bill (PL) 1.229/2024, which is under analysis by the Constitution and Justice Commission (CCJ) of the Federal Senate.

However, drivers and experts should be aware: a similar rule issued by the National Traffic Council (Contran) is already in effect, while changes to the traffic code and criminal rules are still in progress in the National Congress. Understand below how each of the measures works, what changes with the bill and what is already in force on Brazilian roads.

What does Bill 1,229/2024 provide for in the Senate?

Authored by Senator Fabiano Contarato (PT-ES), PL 1.229/2024 provides for the mandatory nature of alcohol and toxicology tests in cases of traffic accidents. The intention is to speed up the forensics and avoid uncertainties about drunkenness at the time of the occurrence.

In addition to the mandatory test, the proposal brings severe changes in the criminal treatment of drunk drivers:

• Arrest in flagrante maintained: the text ends the loophole that prevents arrest in flagrante delicto if the drunk driver provides help or remains at the scene. The evaluation of whether to maintain or revoke the arrest will be exclusively up to the judge at the custody hearing.
• Non-bailable crime: the bill establishes that the crime of manslaughter while driving under the influence of alcohol or drugs will become non-bailable.
• Use of psychoactive substances: requires tests to detect not only alcoholic beverages, but also other drugs.

Contran Resolution No. 1,031/2026: what is already in force?

Although the Bill still depends on votes in the House and Senate to become law, drivers must already comply with Contran Resolution No. 1,031/2026. The administrative rule established immediate guidelines for traffic agents:

1. Inspection in accidents: involved in accidents (with or without victims) must go through inspection procedures whenever possible.
2. Measurement methods: in addition to the breathalyzer and drug detection devices, the authority can verify drunkenness through signs of altered psychomotor capacity.
3. Mandatory examination in accidents with death: in case of death resulting from an accident, a blood or laboratory test is mandatory for official expertise purposes.

What if it is not possible to perform the breathalyzer test?

Both the resolution and the bill consider operational situations in which the breathalyzer test or laboratory examination cannot be done immediately.

In these episodes, the driver’s condition may be verified through:

• Clinical examinations and medical examinations;
• Images and videos of the scene of the occurrence;
• Witness statements.

In all cases, the driver is guaranteed the constitutional right to rebuttal.

What is the current status of the proposal in Congress?

PL 1.229/2024 has already been approved by the Public Safety Committee and is now awaiting an opinion from the Constitution and Justice Commission (CCJ) of the Senate. If approved, it will still need to go through the Senate plenary and the Chamber of Deputies before going to presidential sanction.

It is important to reinforce that the analysis of the project in the CCJ does not mean that the CTB has already changed. However, the driver involved in an accident is already subject to the inspection guidelines provided for in Resolution 1,031/2026 of Contran.