Refusing a Breath Test in Thailand: What Happens

Refusing a breath test in Thailand is not a way of avoiding a drink-driving charge. Under section 142 of the Land Traffic Act, where an officer has reasonable ground to believe a driver is intoxicated and the driver refuses a test without reasonable justification, it is presumed that the driver has breached the prohibition on drink-driving. The refusal itself becomes the evidence.

That is a stronger rule than most visitors expect. In several of the countries our readers come from, refusing is a separate offence — often a serious one, but a different one from being over the limit. Thailand does not work that way. There is no lesser charge to choose. A refusal lands you in the same place as a failed test, and the Royal Thai Police confirmed as much publicly in 2026, stating that refusal is treated as equivalent to drink-driving and carries the same penalties.

• Effect of refusalStatutory presumption that you were drink-driving
• Officer's powerDetention for as long as necessary to complete the test
• Separate offenceDisobeying an order to stop or be tested: up to 1,000 baht each time
• Not a lesser chargeSame penalties as a positive test

What section 142 actually does

Section 142 is the checkpoint provision. Its first two limbs give a traffic officer power to order a driver to stop, and require the officer to order an impairment test where there is reasonable ground to believe the driver is unfit to drive or is intoxicated. Note the wording: the officer shall order the test, not may. Once the threshold is met, testing is not a discretionary choice the officer can be talked out of.

The next two paragraphs are the ones that matter if you say no.

Read together, the two paragraphs close the exit. Refusing does not end the encounter, because the officer can hold you until the test happens. And it does not remove the evidence, because the refusal supplies it.

Where the presumption leads

A presumed breach of section 43(2) is prosecuted as a breach of section 43(2). That means the penalties in drink-driving penalties in Thailand apply in full: up to a year and/or a fine of 5,000 to 20,000 baht for a first offence with no harm caused — roughly £110 to £450 — plus a licence suspension of at least six months or revocation, with much heavier bands where injury or death results.

It also means the case cannot be settled at the roadside. Section 140 removes drink-driving from the warning-and-ticket process, so there is no fixed penalty for an officer to write and no amount for you to pay on the spot. The file goes to an inquiry officer and then to court.

There is a third, smaller offence sitting alongside all of this: disobeying an officer's lawful order to stop or to submit to a test is punishable by a fine of up to 1,000 baht on each occasion, under section 154. It is trivial next to the presumption, but it is worth knowing that the refusal is chargeable in its own right as well as being evidence of something worse.

"Without reasonable justification"

The presumption is not automatic. It applies where the refusal is without reasonable justification, which leaves room for a driver who genuinely cannot provide a breath sample — someone with a facial or chest injury after a collision, for example, or a driver whose medical condition prevents them producing the required breath.

That is not a loophole, because the law has already provided for it. The 2024 ministerial regulation on alcohol testing makes breath the primary method and sets out two alternatives for cases where a breath test cannot be carried out: a urine sample, taken into a sealed container in a private collection area and analysed by a laboratory, or a blood sample taken by medical staff at a hospital. A driver who cannot blow is not therefore untestable; the test simply moves.

Refusing a drug test is a different thing entirely

This distinction is worth being precise about, because plenty of sources blur it. The presumption in section 142 is written for alcohol. It attaches to a refusal to be tested where the officer suspects a breach of section 43(2).

Drugs are handled by section 43 bis and section 157/1. An officer may examine a driver for narcotics or psychotropic substances, and where the preliminary test is negative the driver may continue. If the driver refuses that examination, two things follow: the officer may detain them for as long as is necessary to complete it, and the refusal is itself an offence carrying a fine of up to 1,000 baht. No statutory presumption of drug-driving arises.

So the practical position is that refusing a drug examination is a lesser offence than refusing a breath test — but it also achieves nothing, because you are detained until the examination happens anyway. Cannabis and driving in Thailand deals with the substance most readers are actually asking about, and with why the absence of a measured threshold makes the officer's assessment decisive.

What happens in the room

Thai roadside checkpoints are ordinary and quick — cones, a marked car, two or three officers, a licence check. A breath test at one takes about a minute and, if you are clear, you are waved on. The situation this page describes only arises if you decline.

If you do, expect to be moved off the road and asked again, expect the request to be documented, and expect to be taken to a station rather than released. An interpreter is a reasonable thing to ask for, and calling the tourist police on 1155 gets an English-speaking officer involved — they cannot overrule a traffic officer, but they can make sure everyone understands what is being said. Police checkpoints in Thailand covers the routine version, and your rights as a foreign driver covers the boundary between a traffic stop and something more serious.

Frequently asked questions