In Texas Blood warrants will be used more in DWI cases.

The United States Supreme Court rules that dissipation of alcohol in the bloodstream does not automatically allow law enforcement to involuntarily obtain a blood sample without a warrant in DWI cases. Missouri v. McNeely.

The US Supreme court stated, “The question presented here is whether the natural metabolization of alcohol in the bloodstream presents a per se exigency that justifies an exception to the Fourth Amendment’s warrant requirement for nonconsensual blood testing in all drunk-driving cases. We conclude that it does not, and we hold, consistent with general Fourth Amendment principles, that exigency in this context must be determined case by case based on the totality of the circumstances.”

The Court further rejected the argument by the State as follows, “In those drunk-driving investigations where police officers can reasonably obtain a warrant before a blood sample can be drawn without significantly undermining the efficacy of the search, the Fourth Amendment mandates that they do so. See McDonald v. United States, 335 U. S. 451, 456 (1948) (“We cannot . . . excuse the absence of a search warrant without a showing by those who seek exemption from the constitutional mandate that the exigencies of the situation made

[the search] imperative”). We do not doubt that some circumstances will make obtaining a warrant impractical such that the dissipation of alcohol from the bloodstream will support an exigency justifying a properly conducted warrantless blood test. That, however, is a reason to decide each case on its facts, as we did in Schmerber, not to accept the “considerable overgeneralization” that a per se rule would reflect. Richards, 520 U. S., at 393.”

In Texas, the law allowed for law enforcement and police to take blood from your body without your consent after driving while intoxicated (“DWI”) arrest if you have 2 prior DWI convictions, a child passenger under 15, and/or caused serious bodily injury or death.  See Texas Transportation Code Section 724.

In summary, the Supreme Court’s ruling effectively makes the warrant exceptions provided in Section 724 unconstitutional  because now the police do not automatically have the right to take your blood without your consent unless it obtains a warrant or it is shown that “exigent circumstances” existed that obtaining a warrant was impractical.  Likely, in large cities where a judge or magistrate is available 24/7, it will make it very difficult for prosecutors to argue that not getting a warrant was ok because it does not take very much time to obtain one.  Therefore, I believe that most District Attorney’s Offices will now require law enforcement to obtain warrants before withdrawing blood without ones consent to avoid the potential of a judge throwing out the blood evidence based on it being obtained unconstitutionally based on the US Supreme Court’s ruling in Missouri v. McNeely.

If you have more legal questions about DWI blood tests, see: Texas DWI Blood Test Law