It's not enough to refuse a breath test anymore. If you refuse to take a breath test, the police can obtain a search warrant to draw blood. In Texas, a police officer who has probable cause to arrest a suspect for DWI can obtain a search warrant for your blood. To do so, the officer must submit a search warrant application to a judge. If the judge reviews the search warrant affidavit and finds that there is probable cause, then a search warrant will be issued authorizing a qualified lab tech to collect a blood sample. That blood sample will then be taken by the arresting officer and set to the crime lab for testing. if the blood comes back over the legal limit of .08, it can by offered as evidence of impariment at trial.
The Criminal Defense Blog