New York State just takes one breath sample. It's called "replicate" testing. They (the police) Test one sample twice versus the industry accepted norm of "duplicate" testing whereby they take two separate samples. Many other states do duplicate sampling. Because CSI fans, having two separate and distinct samples (within .02 of each other) assures greater accuracy of the procedures.
Imagine for a moment going to the doctor, and getting a high blood pressure reading on his machine. The doctor makes a hypertensive diagnosis based solely upon the one test, and prescribes medication. How about one better, have a blood test for HIV and you are told it is positive. Sorry no second opinions for you, you just have to live with those results.
Well having a breath machine spit out a number is scary stuff. The machine is an unsworn trial witness. Scarier still is the fact that for the test results to even approach any accuracy the machine operator needs to follow the proper procedures. Couple to that fact that machine breath testing of alcohol ASSUMES: an average body temperature, an average metabolism, an average lung capacity, your body is done absorbing alcohol, and you are healthy we have all the ingredients of an inaccurate test.
An inaccurate test is bad enough but when you only get one opinion (from one test sample) it makes that test critical to your guilt or innocence of DWI "per se" (based on the test). Errors in breath testing generally come from three different areas:
1. Machine errors
2. Operator errors
3. Subject errors
Looking at each of these areas in detail is crucial to mounting an effective DWI defense. Recently, I had a case where the chemicals used in testing were expired prior to doing the test. Technically, the chemicals have a certified expiration date from the NYS Police crime lab but more importantly is that that is a "shelf" life (date) for the chemicals. Once the chemicals are put into use for testing on the machine they can only be used for 60 days ("use" life) from the date of first use. So checking chemical logs (the police must keep weekly logs of the chemicals) against the certified expiration dates is important.