By Ryan Blitz, J.D. Class of 2017 Touro Law Review Senior Staff Member
The Fourth Amendment was intended to uphold individual’s rights to privacy from unreasonable government searches or seizures. Police officers may not conduct a full search of an individual’s person or belongings without a valid search warrant unless some type of exigency or another exception applies. One may wonder, therefore, why police officers can force drivers to take breathalyzer tests or give blood samples after being suspected of drunk driving. Isn’t this a warrantless search?
Drunk driving kills thousands of people every year, becoming one of the most significant dilemmas facing state governments. In order to remediate this growing problem, all fifty states have adopted “implied consent” laws which deem that all drivers have consented to warrantless tests for alcohol simply by driving on state roads. This past summer, in Birchfield v. North Dakota, the United States Supreme Court determined the legitimacy of these warrantless searches, namely, whether states may criminalize the refusal of a driver, arrested for driving while impaired, to take a test to measure his blood-alcohol level. Writing the opinion for the Court, Justice Samuel Alito expressed that while states may criminalize the refusal to take a breathalyzer test, states may not criminalize refusal to take a blood test, absent a warrant as an ordinary incident of an arrest for driving while impaired.
Historically, exigent circumstances, or circumstances justifying a warrantless search or seizure, only apply if an officer is in hot pursuit of a fleeing suspect, or where police fear the imminent destruction of evidence. In Missouri v. McNeely, the Supreme Court noted that natural metabolism of alcohol in the bloodstream does not present an exigency that justifies an exception to the Fourth Amendment’s warrant requirement for blood-testing. While metabolism alone does not create an exigency, officers may still conduct such a search if reasonable under the totality of the circumstances. In order to determine the reasonableness of such searches, the Court applied the common balancing test of weighing the government’s interest in public safety versus the individual’s interest in his or her right to privacy.
The same balancing test was applied to both breathalyzer and blood tests, yet the Court reached different outcomes. It appears that the reason for this is invasiveness. Breathalyzer tests, in general, include negligible physical intrusion. They do not require piercing the skin, there is little likelihood of any enhanced embarrassment from that of any similar arrest, and unlike DNA samples, breathalyzer tests leave no biological sample in the government’s possession.
Blood tests, on the other hand, are physically intrusive as needles must be inserted into the suspect’s skin. This sample can may remain in the government’s possession, and reveal much more about an individual than simply determining the amount of alcohol in their blood, thus potentially increasing the anxiety of the individual. Therefore, the Court determined that the invasiveness of a blood test outweighs the interest of the government, especially when there are reliable and less intrusive alternatives to determine one’s blood alcohol content. 
The impact of this decision will be felt differently depending on the jurisdiction. For example, law enforcement in various Pennsylvania counties has exclusively relied on blood testing in DWI cases. District attorneys in these cases will need to rely on other evidence of the impairment or the case may be dismissed. While this case is a victory for privacy rights, the amount of DWI arrests is unlikely to change. As Justice Sotomayor points out in her concurrence in Birchfield, breathalyzers are a reliable alternative to blood tests, and the time it takes to obtain a search warrant over the phone is typically quicker than it takes to conduct the breath test.
 U.S. Const. amend. IV.
 Welsh v. Wisconsin, 466 U.S. 740 (1984).
Birchfield v. N. Dakota, 136 S. Ct. 2160, 2167 (2016).
 136 S. Ct. 2160 (2016).
 Id. at 2172.
 Id. at 2183-84.
 Welsh, 466 U.S. at 740.
 133 S. Ct. 1552 (2013).
 Birchfield, at 2176.
 Birchfield, at 2177.
 Id. at 2178.
 Steve Marroni, Supreme Court ruling could reduce penalties in some DUI cases, Pennlive (June 30, 2016), http://www.pennlive.com/news/2016/06/supreme_court_dui_pennsylvania.html.
 Birchfield, 136 S. Ct. at 2191-92 (Sotomayor J., concurring); see also Sherry F. Colb, Birchfield v. North Dakota; An Acceptable Compromise, VERDICT, (July 6, 2016), http://verdict.justicia.com/2016/07/06/birchfield-v-northdakota-acceptable-compromise.