Warning: Texas law now requires an ignition interlock device for any person who submits a breath or blood test of .15 or over!

Ignition interlock devices are designed to prevent an alcohol-impaired driver from starting and operating a motor vehicle equipped with the device. The interlock requires a driver to submit a breath sample, which is tested for alcohol concentration before the driver starts a motor vehicle. If the driver provides a breath sample with an alcohol concentration at or above a preset limit, the ignition will not start and will prevent an alcohol-impaired person from driving the vehicle on which the ignition interlock is installed. The device requires that periodic breath tests be submitted after the vehicle is started to prevent a driver from starting the vehicle and then drinking. The interlock also maintains a record of successful and failed breath tests. Interlocks bypass the motivational aspects of deterrence-based and educational approaches and remove the offender's ability to choose to drive while impaired by alcohol.

Although courts have, on rare occasions, ruled ignition interlock programs (or pilot programs) unconstitutional at the trial level, all such decisions were reversed on appeal. Given that ignition interlocks bear a rational relationship to highway safety, a legitimate state interest, and that no suspect class is involved (i.e., race, religion or country of origin), the imposition of ignition interlocks has almost invariably been held to be constitutional provided that appropriate procedural safeguards are in place. The legal review concluded that the use of ignition interlocks under appropriate conditions typically does not violate the Fifth, Eighth or Fourteenth Amendment to the United States Constitution.

Double jeopardy and excessive fines do not raise insurmountable constitutional concerns. Double jeopardy addresses the question of whether the imposition of an interlock device in an administrative setting precludes a court from pursuing a criminal action. Based on a series of court cases in Maryland and elsewhere, the answer is clearly "no." State courts of appeals have ruled that a state can pursue an administrative remedy at the same time it is pursuing a conviction for a criminal offense. The excessive fines clause of the Eighth Amendment to the Constitution does not prohibit the implementation of interlocks. Although the cost of an interlock is not insignificant, this cost does not necessarily rise to the level of an excessive fine or significant deprivation provided that an indigent fund is available for offenders needing monetary assistance. Establishment of an indigent fund would address constitutional issues surrounding the poor, who are not considered to be a "suspect class."

Procedural due process (which included "privileges and immunities" for purposes of this review) addresses the issue of the type of trial or hearing process to which a defendant is entitled. The right to due process applies if a significant life, liberty or property interest is at stake. Courts have consistently held that there is a property interest in a driver's license, but less so if the license has already been suspended or revoked. Provision for judicial and/or administrative hearings prior to the imposition of ignition interlocks would certainly appear to satisfy constitutional procedural due process concerns. Substantive due process addresses the issue of whether the imposition of an interlock device violates (by state action, statute or rule) a fundamental constitutional guarantee. Absent a suspect class (i.e., race, religion or country of origin), courts generally interpret substantive due process in light of a "rational basis test." That is, if the statute, administrative rule or state action pursues a valid government purpose and is applied appropriately, it is constitutional. Since states have a legitimate interest in highway safety, substantive due process is not a barrier to the implementation of ignition interlock license restriction programs.

Current ignition interlock statutes and administrative regulations were grouped into four mutually exclusive categories based on the legal review. The four categories, as well as the number of states in each category and the category's proportion of interlock market share are as follows: (I) No Interlock Statutes or Administrative Regulations (8 states; 0.3%); (II) Administrative Regulations Authorizing Interlocks in an Administrative Setting Only (6 states; 10.8%); (III) Statutes Authorizing Interlocks in a Judicial Setting Only (23 states; 53.3%); and (IV) Statutes or Administrative Regulations Authorizing Interlocks in Both a Judicial Setting and an Administrative Setting (14 states; 35.6%).