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What cops need to know about blood alcohol testing and the Fourth Amendment

Make sure you’re current on your state’s driving while intoxicated and implied consent laws


In this Sept. 21, 2015 photo, Minnehaha County Deputy Sheriff Elliott Crayne installs a car breathlyzer for a participant in the state’s 24/7 Sobriety Program outside the county jail in Sioux Falls, S.D.

AP Photo/Jay Pickthorn

Driving while intoxicated is a serious offense that annually claims numerous victims and causes extensive property damage. States have a vested interest in protecting against the scourge of intoxicated motorists and exercising their enforcement powers in the form of criminalizing motor vehicle operation over a certain blood alcohol concentration. In order to determine BAC, a test must be performed. In order to ensure testing, states have passed implied consent laws that impose a penalty on a motorist who refuses to undergo testing. The preceding sentences paraphrase the opening of Justice Alito’s majority opinion in Birchfield v. North Dakota and set the tone for the remainder of the 38-page decision which determined the constitutionality of implied consent laws. Prior to discussing Birchfield a quick review of earlier case law is necessary.

Schmerber v. California
In 1966 the U.S. Supreme Court’s decision in Schmerber v. California allowed the warrantless, un-consented blood draw from a DWI suspect who had crashed his car. The Supreme Court allowed the warrantless search based on the officer’s belief that he was confronted with an exigent circumstance. The exigency in this case was the normal metabolic dissipation of alcohol in the body. For 47 years Schmerber was the guiding law in this area until the Supreme Court’s decision in Missouri v. McNeely (2013). The McNeely case involved facts similar to Schmerber except the Court in McNeely found there was no automatic exigency for a motorist’s blood draw based on the normal dissipation of alcohol in the body. In the McNeely case the Supreme Court held that once the motorist refused a breath test, despite the receipt of warnings under the state’s implied consent laws, any further forcible testing involving a blood draw required a warrant. Though McNeely did not overrule Schmerber it did limit its scope. While the Schmerber rule that exigent circumstances justify warrantless blood draws remains in force, the Supreme Court said that dissipation of alcohol in the motorist’s body was not a sole criterion for establishing an exigency. The aftermath of McNeely was to leave in doubt the status of state implied consent laws while providing defense attorneys with an added means to challenge BAC tests.

Three cases later
However, three short years later and the Supreme Court would have the opportunity to address the questions left in the wake of McNeely.

Birchfield v. North Dakota was the lead case in a trio of consolidated cases, two from North Dakota and one from Minnesota, in which the issue was whether warrantless searches for blood alcohol evidence under a state’s implied consent laws were constitutional. In the title case, Danny Birchfield refused a blood draw test upon his arrest for DWI and was charged with a misdemeanor violation of the refusal statute. Birchfield entered a conditional guilty plea but argued that criminalizing his refusal was a Fourth Amendment violation.

In the second case, Bernard v. Minnesota, William Bernard refused a breath test and was charged with test refusal in the first degree. He too argued that the warrantless test (here though it was a breath test) was not permitted under the Fourth Amendment.

The last case, Beylund v. Levi, Director North Dakota Department of Transportation, did not involve a refusal. Instead, the vehicle operator, Steven Beylund, agreed to have his blood drawn, but later argued on appeal that his consent to the blood draw was coerced by the officer’s reading of the implied consent warning.

The Supreme Court was presented with three very distinct circumstances that begged a resolution of the same issue—the constitutionality of warrantless testing under a state’s implied consent laws. The Supreme Court’s holding was that breath tests incident to arrests for drunk driving do not require a warrant but blood tests do. Breath tests, the Supreme Court reasoned, were less intrusive and do not invoke the same privacy concerns as blood tests.

The level of intrusion into a privacy interest has always been a consideration in the Supreme Court’s assessment of reasonableness under the Fourth Amendment and proceeding to search without a warrant (for example, the Supreme Court’s distinction in the dog sniff cases United States v. Place and Florida v. Jardines).

A blood draw, by contrast, was more intrusive, involving an actual puncture of the individual’s skin and extraction of bodily fluid. In addition, the Supreme Court noted, unlike a breath sample, which dissipates upon testing, a blood sample may be held by police and subjected to additional testing. The compelling interest states have in deterring driving while intoxicated offenses does not vitiate the privacy interest implicated by a blood draw. Further, the Supreme Court noted that the reasonableness of blood tests were to be judged in light of the availability of the less invasive alternative of a breath test.

The criminalization of a refusal to submit to a blood draw under a state’s implied consent law was therefore unconstitutional. A civil penalty was permitted, as was the admission into evidence of a motorist’s refusal, but a criminal penalty for refusal to submit to an intrusive blood test was pushing beyond the acceptable limits of that to which a motorist has consented to upon being licensed by the state to operate a motor vehicle.

Three different outcomes
For the three named petitioners in each case the outcome was different.

  1. Birchfield’s prosecution was overturned based on the warrantless blood draw and the state’s lack of any exigent circumstances justifying the seizure of the evidence.
  2. Bernard, who refused a breath test, had his prosecution upheld since the Fourth Amendment did not require officers to obtain a warrant prior to securing a breath sample.
  3. Beylund’s case was remanded back to the North Dakota Supreme Court to determine, from the totality of circumstances, whether he voluntarily consented to the blood draw or was in fact coerced.

The impact on patrol officers is for them to review their state’s driving while intoxicated and implied consent laws. Birchfield will impact only those states wherein a refusal of a blood draw is a criminal offense. However, it remains under the McNeely decision that a blood draw in connection with a DWI arrest must be conducted pursuant to a search warrant, unless exigent circumstances exist other than natural dissipation of blood alcohol content in the body.

Terrence P. Dwyer retired from the New York State Police after a 22-year career as a Trooper and Investigator. He is a tenured professor of legal studies at Western Connecticut State University and an attorney consulting on law enforcement liability, disciplinary cases, critical incidents, and employment matters. He is the author of “Homeland Security Law: Issues and Analysis,” Cognella Publishing (2024).