Where I live it's customary for the police to announce the locations of DUI checkpoints on days that people are especially likely to be drinking and driving (e.g. New Year's Eve). For awhile I didn't understand why they would do this (and I know a lot of people who still don't get it).
If your goal is to catch people driving drunk, then no, it doesn't make sense to announce the locations of DUI checkpoints. If however your goal is to prevent people from driving drunk in the first place, it might make sense to announce checkpoints at a number of locations throughout the city. If the potential drunk driver knows he can't go too many places without passing though a checkpoint he may decide to just stay home.
1. It hops to discourage people from drinking and driving in the first place by planting the idea that there will be checkpoints. The best time to avoid DUIs is before the driver starts drinking. Ideally, they'll make alternative arrangements to get home from wherever it is they're going rather than taking the car and figuring it out after;
2. To enable those capable of driving to avoid the checkpoints. The premise for this is that those who are drinking and driving either are capable of making this kind of rational forethought or they're not and the police are largely interested in catches those that aren't; and
3. Possibly to divert those that are borderline cases from driving through areas where they might cause the most damage if something does go wrong.
I know people like to see speed traps and DUI checkpoints as cynical revenue-raising initiatives but you'd be surprised to learn that some people just don't want others to act irresponsibly by driving several tons of metal at high speed while impaired, possibly harming or killing themselves or others.
My assumption was always that they did these announcements so that people would be inconvenienced and could avoid the checkpoints. The rationale being that if you're too drunk to drive, you probably forgot about the checkpoint anyway and are likely to get caught.
IANAL, but it is my understanding that police announce checkpoints for legal reasons. And if that is the case and the reasons are based on Federal Law or Constitutional decisions, it makes the request by Senators entirely inappropriate.
If your goal is to catch people driving drunk, then no, it doesn't make sense to announce the locations of DUI checkpoints. If however your goal is to prevent people from driving drunk in the first place, it might make sense to announce checkpoints at a number of locations throughout the city. If the potential drunk driver knows he can't go too many places without passing though a checkpoint he may decide to just stay home.