It looks like NY DWI cases will become more interesting in light of Melendez-Diaz (129 S.Ct. 2527), which just came down from the Supreme Court in late June. That case follows on the 2004 Crawford (541 US 36, 124 S.Ct. 1354) decision on the Confrontation Clause in the Sixth Amendment.
The defendant in a criminal case has the right to confront his accusers. Melendez-Diaz holds that lab technicians who certify things like the nature and quantity of a substance (cocaine in the case) are subject to Crawford. The prosecution merely offered a certificate from the lab without bringing the actual technician. Since the defense did not have the opportunity to confront and cross-examine these witnesses, the evidence should not have been allowed and the conviction was reversed.
This matters for DWI cases in New York. It is routine for the prosecution to rely on certificates to prove that the breath test device (commonly called a breathalyzer but in NY most police use a "Datamaster") is reliable. This includes not only calibration of the device, but also of the "reference solution." Per Melendez-Diaz, the prosecution will now have to bring in the individual who did these calibrations, so the defendant can cross-examine that person.
For those who might argue that this doesn't apply to this kind of DWI evidence, Justice Scalia's opinion squarely addresses this (129 S.Ct. at 2533):
As the dissent notes, three state supreme court decisions from the early 20th century denied confrontation with respect to certificates of analysis regarding a substance's alcohol content. ... But other state courts in the same era reached the opposite conclusion.
Thus, in rejecting the dissent's arguments, Scalia specifically noted the situation with certificates regarding alcohol tests -- this is exactly what the reference sample is, and is also analogous to the calibration of the device. DWI defense lawyers should be ready to argue Melendez-Diaz in suppression hearings and at trial. This should really come up in a pre-trial Ayala hearing.