Checkpoints are a primary tool for DWI enforcement in New York City. The fourth amendment to the U.S. Constitution protects individuals against "unreasonable" searches and seizures. To many of us, that would suggest that agents of the government cannot stop you while you are seemingly doing nothing wrong, unless they have a reason. Generally speaking, that is the law. The police need an actual reason to stop you. However, with respect to DWI car stops, there is, as one famous DWI defense lawyer put it, a "DWI exception to the Constitution."
The leading checkpoint case in New York is People v. Scott. In that case, New York's Court of Appeals upheld the use of checkpoints subject to conditions. Specifically, the court emphasized that checkpoints could not intrude to "an impermissible degree" upon motorists privacy, that they had to be conducted in a uniform manner with little discretion allowed to individual officers, and that adequate precautions needed to be taken to insure that the checkpoint was safe, well lit, and provided sufficient advance notice to approaching motorists. Whether a particular checkpoint is lawful depends upon the existence of specific instructions from a supervisor and the discretion afforded individual officers. The U.S. Supreme Court, in a case called City of Indianapolis v. Edmond, added a requirement that checkpoints not be employed for "generalized crime control." What this means is that border checkpoints and DWI checkpoints are allowed if done properly, but checkpoints to catch everyday criminals are not permitted.
If you approach a checkpoint in New York City, it is usually configured in such a way so that you cannot get out of the line. While the law seems to suggest that checkpoint evasion is not illegal and is not a valid basis for a stop, deliberately avoiding a NYC checkpoint would be difficult and would probably get you pulled over. In the event that you find yourself stopped at a checkpoint after having one or more drinks, the goal should be to avoid being asked to get out of your car. The best advice I can offer is to be polite and to maintain a pleasant but serious demeanor. The officer will always ask you if you have had anything to drink. If you say yes or decline to answer you will almost certainly be asked to get out of your car for further investigation. If you answer no, you may not be asked to get out of your car if the officer does not have any other reason to suspect that you are drunk.
If you have had anything to drink in New York City and you are driving across the Hudson River, my personal suggestion is to avoid the Lincoln or Holland Tunnels as the NYPD frequently sets up checkpoints at these locations. The George Washington Bridge may, in my view, be a better bet.