AUSTIN — Texas’ controversial law allowing police to collect blood samples without a warrant from drivers who refuse is unconstitutional, the Texas Court of Criminal Appeals ruled Wednesday.

While the 5-4 decision is expected to be appealed, it appears certain it will affect so-called “no refusal” enforcement in some Texas jurisdictions. Under the ruling, law enforcement officers would be required to obtain a search warrant before they force suspected drunken drivers to submit to a test measuring their blood-alcohol content.

Many cities — including San Antonio — already have started doing that, making sure judges are available at all hours to sign warrants.

The so-called “no refusal” enforcement drives have been controversial for years, and the Legislature has revised the wording of the current law in an attempt to make it pass constitutional muster. In its decision, the Texas Court of Criminal Appeals said it did not.

“We hold that a nonconsensual search of a DWI suspect’s blood conducted pursuant to the mandatory-blood-draw and implied-consent provisions in the Transportation Code, when undertaken in the absence of a warrant or any applicable exception to the warrant requirement, violates the Fourth Amendment,” Judge Elsa Alcala wrote on behalf of the five majority opinion judges.

Four members of the nine-judge court dissented.

In Bexar and Harris counties, the ruling will have no impact because the district attorney’s offices already seek search warrants in all cases where DWI suspects refuse a breath test or blood draw.

It has long been policy in Bexar County, which has had “no refusal” weekends since 2008 and an around-the-clock program since 2011, to obtain warrants for misdemeanor DWI cases. For the more serious felony cases that didn’t previously require warrants under Texas law, the district attorney’s office began requiring them anyway in April 2013. The change came after the U.S. Supreme Court ruled in a Missouri case that raised questions about the legality of obtaining blood samples without a warrant.

“In an abundance of caution, we’re going to be changing our procedures,” First Assistant District Attorney Cliff Herberg said at the time.

The Supreme Court did not at the time address states like Texas that have statutes allowing mandatory blood draws under certain circumstances.

The Texas Court of Criminal Appeals ruling stems from the 2012 case of David Villarreal, who was pulled over in Nueces County for a traffic violation. After refusing to perform sobriety tests in the field, Villarreal was arrested and taken to a local hospital to have his blood drawn against his will and without a warrant. The arresting officer said the move was legal because state law requires the taking of a breath or blood sample of anyone previously convicted two or more times of driving while intoxicated, which enhances the charge to a felony.

The state asked the trial judge to sentence Villarreal, who had been convicted of felony DWI in 2001 and 2005, to at least 25 years in prison. However, defense attorney Fred Jimenez cited the Supreme Court case. The trial court agreed, saying the blood sample and the evidence it produced — that Villarreal’s blood-alcohol content of 0.16 — was inadmissible.

Jimenez said while he is pleased with the ruling, it does not mean police officers no will longer be able to take blood and breath samples against a DWI suspect’s will. They just need to ensure they have a warrant first.

“We’re not going to see the end of no-refusal weekends, but the procedure has changed,” said Jimenez, who added he suspects the state will appeal the ruling to the U.S. Supreme Court and also take his client to trial on other evidence.

“All it is, is a ruling that they cannot use the blood test that they obtained without a warrant. That’s all it is. They can still try my client,” said Jimenez. “It’s a weaker case without that evidence. There’s a videotape of my client, and he looks good on the videotape.”

Officials with the Nueces County district attorney’s office had no immediate comment.

Staff Writers John Tedesco in San Antonio and Anita Hassan in Houston contributed to this report.

lauren.mcgaughy@chron.com

mike.ward@chron.com