While an argument can be made that simply installing alcohol detectors in cars may be permissible under the Constitution, that argument falls apart when blowing into one to start the car becomes mandatory. Since there are no additional inherent safety risks in starting a car, a warrant-less requirement to blow into an alcohol detector to start a car amounts to an unreasonable search. Likewise, the inability to start the car when the device detects an out-of-the-norm condition amounts to an unreasonable seizure.
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
The Constitution limits what the federal government can do and gives all other powers to the people and the states. It does not say that ideas, which may make for good social policy, should be implemented. Even though it limits what the federal government can do, the Constitution also provides a sound basis for good local policy.
Since the Constitution is pretty clear on our rights to be free from unreasonable searches and seizures, One Black American asks, "Why is it a good idea for citizens to give up Fourth Amendment rights and acquiesce to bad ideas? Indeed, why is it even a good idea for citizens to give up Fourth Amendment rights and acquiesce to good ideas?"