There are 4 basic types of felony DWI in the Texas Penal Code.
The most common of these is probably DWI third, that is, a new DWI charge with two prior convictions. It used to be the law in Texas that if ten years passed from the date of the last DWI conviction, that the new charge was “only” a Class B Misdemeanor, and treated like a DWI first. Then the legislature made it 10 years from the date the person was released from confinement, or probation or parole. More recently, the ten year requirement was abolished, and any prior DWIs are usable for enhancement. This includes out of state DWIs.
The newest type of felony DWI charge is listed in the DWI Chapter of the Penal Code at Section 49.045, DWI with Child Passenger. This statute elevates even a first DWI charge to the level of State Jail Felony, if there is a child under 15 years old in the car. Very often, the State has the same problems proving intoxication that they would in a “regular” DWI charge. However, there are rarely substantive issues regarding the age of the passenger. No prior convictions are required for this to be indicted as a felony.
A third type of Felony DWI in Texas is Intoxication Assault. Section 49.07 is essentially a DWI, with the additional element that the defendant “by accident or mistake…and by reason of …intoxication causes serious bodily injury to another”. There are three basic defenses here: (1) the Defendant was not intoxicated, (2) the injury does not fall into the legal category of “serious bodily injury”, and (3) the intoxication did not cause the injury or accident. No prior convictions are required.
The fourth and final type of Felony DWI is Intoxication Manslaughter. Section 49.08 covers DWI is similar to 49.07, except that the intoxication causes death instead of serious bodily injury. Fortunately, this is the probably the least common type of DWI charge. Both Intoxication Assault and Manslaughter cases usually involve forced blood draws, and are therefore more difficult to defend than other cases. (Blood tests over .08, while not unassailable, are more reliable than breath tests from the intoxilyzer, at least in my opinion.)