Most Rochester area drinking and driving offenses involve the driver being asked to submit to a breath test to determine his or her blood alcohol content.

In some cases, however, the defendant will be asked or compelled to take a blood test instead.

This may happen where the circumstances surrounding the arrest involved a motor vehicle accident which led to serious physical injury or death.

It also has been known to happen simply because the breath test machine normally used by the police department is not working.

Blood tests typically involve providing a blood sample, which is then sent to a laboratory to be tested using gas chromatography.

Just as the prosecution in a breath test case must submit some evidence that the breath test machine was working properly before the breath test result can be submitted as evidence at trial, in blood test cases there must be evidence that the gas chromatograph used to test the defendant’s blood was working properly at the time of the test.

New York State regulations surrounding the testing of blood or urine for alcohol content require that for any sample or series of ten samples analyzed sequentially or simultaneously, the machine used to test the blood or urine demonstrate the ability to accurately analyze (1) a blank sample (one containing no alcohol) as appropriate; and
(2) a suitable reference sample of known alcoholic content greater than or equal to 0.08 percent weight per volume.

The results of this reference standard analysis must agree with the known value of the sample within plus or minus 0.01 percent weight per volume.

While blood test cases can be more difficult than breath test cases, an experienced DWI lawyer will still examine all of the evidence surrounding the test to ensure that it was conducted properly.

If you have been arrested for DWI and need legal help, we can be reached at 585-484-7432.