Implied Consent

The legal term implied consent refers to situations in which it is assumed a person consented to something by his actions. This means that, although the person has not given verbal or written consent, circumstances exist that would cause a reasonable person to believe the other had consented. Questions of implied consent arise in a variety of situations, including medical care, contracts, and even actions that may be considered criminal if no consent is given, such as rape. To explore this concept, consider the following implied consent definition.

Definition of Implied Consent


  1. The assumption that a person has given permission for an action, which is inferred from his or her actions, rather than expressly or explicitly provided.


1965-1970       American legal term

What is Implied Consent

There are many situations in which people must give consent in order for something to happen. For instance, an individual must give consent to be treated by his doctor, consent to allow a mechanic work on his car, and consent to allow his attorney to represent him in a legal matter. In some cases, a person may be unable to give verbal or written consent – for instance, if he is unconscious – yet certain actions are necessary. A

s an example of implied consent, should Alan be knocked unconscious at his job on a construction site, he cannot give paramedics consent to treat him, yet it is clear he needs help. In such a case, it is implied that Alan would consent, should he be able, and the paramedics treat him as such.

Implied consent is used in other areas as well, such as law enforcement testing of drivers suspected of driving under the influence (“DUI”), and contracts are often undertaken by implied consent, without the parties even realizing it.

Implied Consent Laws

Implied consent laws exist in all jurisdictions, and cover a broad variety of circumstances. Implied consent may be assumed in medical situations, legal representation, contract issues, and others. Implied consent laws are intended to protect both the person who is assumed to have given consent by his actions or circumstance, and in some situations, to protect others. As an example of implied consent protecting others, most states have implied consent laws that are inherent in driving on any public roadway.

In such instances, anyone suspected of driving under the influence has impliedly consented to submit to blood, breath, or urine tests to determine the nature and level of intoxication. Even though such a driver may not give explicit consent, consent is implied by the act of accepting a driver’s license, and by getting into the car and driving on a public road.

Implied consent laws are frequently challenged for a number of civil rights reasons, primarily in DUI cases. Many, many people charged with DUI have claimed that forcing them to submit to testing violates their Fourth Amendment right against unreasonable search and seizure, as well as their Fifth Amendment right to avoid self-incrimination. The courts have generally upheld implied consent laws as being constitutional, though they have invalidated laws that allow the states to revoke someone’s license without first holding a hearing.

Legality of Implied Consent in DUI Cases

While implied consent in DUI cases are the most challenged, the courts in the U.S. have adopted two philosophies regarding the legality of implied consent in DUI cases:

  1. Driving is a privilege – Nobody has a right to drive on public roads and highways. Only those people who obey the laws, including those prohibiting driving under the influence, are offered that privilege.
  2. State’s Police Power – In weighing the best interests of society against the interests of individuals breaking the law by driving under the influence, the courts have determined that impaired drivers are indeed a danger to society. Because of this, implied consent laws are considered to be a reasonable assumption to exercise the state’s police power.

Drunk Driving Implied Consent

Every state in the U.S. has driver licensing laws that specify that anyone who obtains a drivers’ license has automatically given his implied consent to be subjected to certain tests to determine whether his is driving under the influence of alcohol or other substance. This generally includes being required to submit to a field sobriety test and/or a breathalyzer test, and in some cases, a blood test.

Under DUI laws, refusing to take such tests when directed by a law enforcement officer may result in suspension of the individual’s driver’s license, and often stiffer penalties. The reason the courts have held that DUI implied consent laws are constitutional, is that there is an implied responsibility to protect the public from property damage, personal injury, or even loss of life.

For example:

Martin stopped at the local sports bar to have a couple of drinks with his friends after work. An hour later, having downed “a couple of beers,” Martin gets in his car to head home. A police officer, who sees Martin swerve too close to the curb, then swing wide to narrowly avoid hitting a parked car, stops Martin.

The officer smells alcohol on Martin’s breath, and can tell he isn’t too steady, so he gets him out of the car, and asks him to take a breathalyzer test. Martin is indignant as he refuses and berates the officer, claiming that he must have been sitting across the street from the bar bent on pulling over a large number of cars to make a “quota.”

In this example of implied consent, Martin can choose not to take the breathalyzer test, or any of the other tests the officer recommends, but he does not have a right to do so without consequences. Because he had automatically given implied consent when he obtained his drivers’ license, he cannot claim invasion of privacy, or unreasonable search and seizure.

Medical Consent

Some type of consent must be given before any medical treatment can be rendered. There are two types of consent that may be obtained by medical personnel: (1) informed consent, and (2) implied consent.

Informed consent requires that the patient be given enough information about his condition, and about his treatment options, to be able to make an informed choice about his care. Only competent adults can give informed consent, which means the patient must be age 18 or older, be able to understand the information given to him, and to make a well-informed decision. Informed consent may be given verbally, but normally involves signing documents prior to treatment. A minor may not give medical consent, so consent must be obtained from his parent or legal guardian.

Implied consent exists, in the medical field, to allow medical professionals to render emergency treatment to patients who cannot give informed consent, and for whom no immediate family can be reached to make such decisions.

For example:

Wilma is involved in a car accident, and rushed to the hospital unconscious. The emergency room doctor determines that Wilma is suffering from life-threatening internal bleeding, and that she needs immediate surgery. Wilma cannot give consent, and nobody has been able to reach any family members.

In such a case, it is assumed that Wilma would consent to life-saving emergency surgery, so the law recognizes this as implied consent. In this example of implied consent, even if Wilma later became angry, claiming she had not consented to the surgery, it is unlikely she would have a legal claim (based on consent), as consent is implied in such situations.

Implied Consent Example in Civil Rights Litigation

One November evening in 1964, Armando Schmerber was driving home after drinking at a local bowling alley/tavern in Southern California, when he lost control of his car, which slid off the road, and hit a tree. Schmerber and his passenger were injured and taken to the hospital. When the police officers arrived at the hospital to question Schmerber, they asked him to submit to a blood test to determine his blood alcohol level. When Schmerber refused, the officers instructed the medical personnel to take a blood sample anyway.

The results of the blood test, from the sample taken without a search warrant, showed that Schmerber was indeed intoxicated by the legal definition, and he was arrested. The blood sample was submitted as evidence at Schmerber’s trial, and he was convicted. Schmerber appealed his conviction, claiming that the taking of a blood sample without his consent, and without a search warrant, violated his civil rights to be protected from unreasonable search and seizure, his right to due process, his protection against self-incrimination, and his right to counsel. The prosecution had based its case on the principle that, by driving on the public roads, Schmerber had given implied consent to be subjected to DUI testing.

The matter was heard by the U.S. Supreme Court, which had previously established that searches that require intrusions into the human body require a search warrant. The Court ruled in Schmerber’s case, however, that there were pressing circumstances which allowed an exception, as, should the officers have waited to receive a search warrant, Schmerber’s body would have metabolized and gotten rid of the alcohol in his blood stream. This created what the officer could reasonably have considered to be an emergency, as evidence was being destroyed every minute they waited. The Court also noted that the taking of a blood sample is a minimally intrusive act, making it even more reasonable in this specific situation.

From this case, and others like it, implied consent laws were developed in each state over the years, making it legal for police officers to require testing as approved by law, of drivers suspected of being under the influence. Over the years, more accurate, and less intrusive testing has been developed, and not most states recognize implied consent for field sobriety tests, breathalyzer tests, and even urine tests. More recent rulings of the Supreme Court have held that, in most cases, a search warrant is required to obtain a blood sample, or for any other evidence searches that intrude into a suspect’s body.

Related Legal Terms and Issues

  • Breathalyzer – A device used by police to estimate a driver’s blood alcohol content by sampling the driver’s breath.
  • Civil Rights – The rights belonging to an individual by virtue of citizenship, especially the fundamental freedoms and privileges guaranteed by the 13th and 14th Amendments.
  • Due Process – The fundamental, constitutional right to fair legal proceedings in which all parties will be given notice of the proceedings, and have an opportunity to be heard.
  • Impaired Driver – A person operating a motor vehicle while his mental capacity is diminished by distractions, fatigue, alcohol, medications, or illegal drugs.
  • Search Warrant – A court order that authorizes law enforcement officers or agents to search a person or a place for the purpose of obtaining evidence or contraband for use in criminal prosecution.
  • SelfIncrimination – The act of implicating oneself in a crime, or of exposing oneself to criminal prosecution.