What Is the Implied Consent Law?

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When police stop a driver with suspicion of DUI, they ask the driver for a field sobriety test, including the use of a breathalyzer. Police officers can't physically force anyone to blow into a tube, but refusing this test has its own consequences because of a concept known as implied consent. Under the implied consent laws, which are valid in all states, the act of applying for a driver's license includes the agreement that the driver will submit to chemical and field sobriety tests if requested.

What is the Difference Between Implied and Informed Consent?

People have a legal right to decide what happens to their bodies, and doctors have an ethical duty to involve their patients in their own care. The concept of informed consent protects a person's right to control his own body. If you're being asked to undergo a medical procedure, such as a blood test, you have the right to know the risks of the proposed procedure and to determine whether the risks are worth proceeding. In order for informed consent to be valid, it must also be voluntary.

Implied consent may seem like the opposite of informed consent, when it comes to giving permission for blood tests and other invasive procedures, but they're actually the same thing along a different timeline. You give informed consent long before the possible DUI occurs, thereby creating a condition of implied consent.

Read More: Difference Between Express Consent & Informed Consent

How Does Alcohol Affect You Behind the Wheel?

There's a reason driving while impaired is so dangerous: it affects every sense that you need to make good decisions and drive safely. Some of the most important ways it can affect you behind the wheel are:

  • Lack of coordination. Drinking affects your foot, hand and eye coordination, which can affect your ability to avoid dangerous situations. Too much alcohol can even make it hard to find your car or put the key in the ignition slot.
  • Slow reaction time. You respond to different situations much more slowly when you have alcohol in your system. If someone runs out into the road in front of you, or if the car next to you suddenly swerves into your lane, you may not react quickly enough to prevent an accident.
  • Decreased vision. Too much alcohol can make your vision blurry, or can make it difficult for your eyes to track moving objects. It can make it hard to judge distances between your car and other objects on the road around you. In addition, your peripheral vision, or the objects you can see beside you, fade away with too much alcohol on board.
  • Reduced concentration. Any amount of alcohol affects your concentration to some extent. Driving tasks such as staying in your lane, watching for other cars, keeping under the speed limit and obeying traffic signs all require complete concentration. If you're not paying attention, your chances of getting into an auto accident are much higher.
  • Impaired judgement. Your judgement skills play an important part in the million decisions you make while driving a motor vehicle. You need to look ahead, predict what other drivers are likely to do, and react accordingly. Without clear judgement you won't have the ability to make the right decisions that keep you and others safely on the road.

Can You Refuse a Breathalyzer Test?

If you're pulled over for suspicion of DUI, the officer has no legal right to force you to blow into the breathalyzer machine, regardless of the implied consent laws. You have every right to refuse to take the test. However, there are real consequences for doing so. Refusing the test means you understand these consequences and accept that they will likely happen to you.

The officer may still arrest you, based on other evidence she observes and collects. In some jurisdictions, the fact that you refused the test can be used against you in criminal court. In addition, part of the implied consent law states that you are giving consent in order to receive driving privileges. If you refuse the test, you are, in effect, giving up your right to drive. Depending on the state, you can lose your license for up to a year, and if you have prior DUI convictions, it can be even longer, or involve jail time.


  • Part of a driver's license application in all states is that, if pulled over, the driver will agree to field sobriety and breathalyzer tests. This is known as the implied consent law.