Last September in this blog we published a post about the consequences of refusing a breath test under Texas' implied consent statute. Every driver in Texas has the right to refuse a breathalyzer test, but there are consequences to that refusal. One of the possible consequences is that the arresting officer can contact a judge and get a warrant to take a blood test.
In 2013 the U.S. Supreme Court ruled that officers need a search warrant to conduct a blood test after a breath test refusal. Texas law enforcement officials continued to conduct warrantless blood tests in felony DWI arrests and other situations they believed were not covered by the Supreme Court ruling. Last November, however, the Texas Court of Criminal Appeals ruled that a search warrant is required any time an officer seeks to conduct an involuntary blood test.
To obtain a warrant for a blood test, the arresting officer must prepare an sworn application stating the officer has probable cause to believe the driver is intoxicated, and that the driver has refused a breath test. The application must be approved by a judge before the warrant is issued.
When a driver is charged with drunk driving after a blood test warrant, one of the first things a DWI defense lawyer will do is investigate whether there was probable cause for the warrant to be issued. If there was not, the blood test evidence can be suppressed and the charges may be dismissed. The accuracy of the blood test itself can also be challenged in many cases.
Source: Findlaw, State v. Villarreal (Tex. Ct. Crim. App. Nov. 26, 2014), accessed Mar. 1, 2015