Implied consent is consent which is not expressly granted by a person, but rather implicitly granted by a person's actions and the facts and circumstances of a particular situation (or in some cases, by a person's silence or inaction). The term is most commonly encountered in the context of United States drunk driving laws.

Driving while intoxicated

All U.S. states have driver licensing laws which state that a licensed driver has given their implied consent to a certified breathalyzer or by a blood sample by their choice, or similar manner of determining blood alcohol concentration.[1] Implied consent laws may result in punishment for those who refuse to cooperate with blood alcohol testing after an arrest for suspected impaired driving, including civil consequences such as a driver's license suspension.[2]

In 2016, the Supreme Court of the United States in Birchfield v. North Dakota held that both breath tests and blood tests constitute a search under the Fourth Amendment, concluding that requiring breath tests is constitutional without a search warrant, however, requiring more intrusive blood tests involving piercing the skin is not, as the goal of traffic safety can be obtained by less invasive means.[3] Specifically addressing implied consent laws, the court in the Birchfield opinion stated that while their "prior opinions have referred approvingly to the general concept of implied-consent laws" that "there must be a limit to the consequences to which motorists may be deemed to have consented by virtue of a decision to drive on public roads" and "that motorists could be deemed to have consented to only those conditions that are 'reasonable' in that they have a 'nexus' to the privilege of driving".[4]

In other contexts

Court procedure

Typically, a party has the right to object in court to a line of questioning or at the introduction of a particular piece of evidence. If the party fails to object in a timely fashion, he is deemed to have waived his right to object and cannot raise the objection on appeal. This is a form of implied consent.[5]

In California, "Any person providing the [California Department of Motor Vehicles] with a mailing address shall … consent to receive service of process …".[6]

Sexual assault

In Canada, implied consent has not been a defence for sexual assault since the 1999 Supreme Court of Canada case of R v Ewanchuk, where the court unanimously ruled that consent has to be explicit, instead of merely "implied".[7]

Spousal rape

In many common law jurisdictions, a couple who married were deemed to have given "implied consent" to have sex with each other, a doctrine which barred prosecution of a spouse for rape. This doctrine is now considered obsolete in Western countries.[8]

First aid

In the United States, if a person is at risk of death or injury but unconscious or otherwise unable to respond, other people including members of the public and paramedics may assume implied consent to touch the person to provide first aid.[9] Many states have Good Samaritan laws that protect persons giving aid from legal liability, but the type of persons (laypeople versus healthcare professionals) and the amount of protection varies.

Organ donation

Some countries have legislation allowing for implied consent for organ donation, asking people to opt out of organ donation instead of opt in, but allow family refusals.[10]

See also


  1. ^ Soronen, Lisa. "Blood Alcohol Testing: No Consent, No Warrant, No Crime?". NCSL. National Conference of State Legislatures. Retrieved 30 October 2017. 
  2. ^ Larson, Aaron (23 August 2016). "Blood Alcohol Testing in Drunk and Impaired Driving Cases". ExpertLaw.com. Retrieved 30 October 2017. 
  3. ^ Marimow, Ann E. (June 23, 2016). "Supreme Court requires warrants for some, but not all drunken-driving tests". The Washington Post. Retrieved 1 September 2017. 
  4. ^ "Birchfield v. North Dakota, Opinion of the Court" (PDF). p. 36-37 (41-42 of pdf). Retrieved 2 September 2017. 
  5. ^ "Implied Consent". jrank. Net Industries. Retrieved 30 October 2017. 
  6. ^ California Vehicle Code § 1808.21(c)
  7. ^ "No still means "no": Editorial". thestar.com. The Toronto Star. November 13, 2015. Retrieved October 13, 2016. 
  8. ^ See e.g. R v R [1992] 1 AC 599
  9. ^ Brouhard, Rod (29 October 2017). "Before You Save a Life: Understanding Medical Consent". verywell. Dotdash. Retrieved 30 October 2017. 
  10. ^ Keeping kidneys, Bulletin of the World Health Organization, Volume 90, Number 10, October 2012, 713-792 [1]

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