Yes, DUI checkpoints are legal.
That could have made for a very short post, but allow me to expand by explaining why DUI checkpoints are generally legal. (I say generally because there can still be situations where a particular DUI checkpoint could be found illegal. Not all roadside sobriety checkpoints are necessarily set up and administered in a constitutionally permissible manner.)
Nevertheless, courts in the majority of states have upheld DUI checkpoints against challenges that these checkpoints are unconstitutional. Interestingly, courts have not upheld drug checkpoints.
When opponents have challenged DUI checkpoints, it has usually been on the grounds that they are a violation of the 4th Amendment to the U.S. Constitution's prohibition against unreasonable searches and seizures. However, when courts have tackled the issue, they have ruled that the intrusion of checkpoints is justified by the seriousness of drunk driving and the possible deterrent effect of sobriety checkpoints.
A landmark California case will shed some light on this for us. The California Supreme Court, in Ingersol v. Palmer, named a number of factors that they would consider when determining whether a given DUI checkpoint was legal. Here are a few of the factors from the 1987 case:
Putting the legalities aside for a moment, DUI checkpoints or not, it doesn't make sense to drive after drinking on New Years. If you are intoxicated tonight, you can call 1-800-AAA-HELP, and AAA will give drivers a free one-way ride home for them and their vehicles, up to 10 miles away. Or, a simple Google search turns up a number of free ride services designed to keep you safe after you ring in 2011.