When a Rochester driver takes the breath test after being stopped on suspicion of drinking and driving, the breath test machine uses a mixture known as a “simulator solution” to test the accuracy of the machine.

The simulator solution contains a known amount of alcohol.If a simulated breath test using this solution yields the correct result, there is a presumption that the machine is working accurately.

When a driver takes a blood test, a similar solution is used to test the gas chromatograph machine thatmeasures the alcohol content of the driver’s blood.

In a typical case, a chemist using gas chromatography to test for alcohol starts with pure ethyl alcohol.

The alcohol is then mixed with de-ionized water to make a standard solution – similar to the simulator solution – which is then tested for alcohol content.

The testing of the standard solution allows the chemist to properly set and adjust the gas chromatograph and produces a benchmark against which the test of the defendant’s blood is compared.

In a breath test case, New York State law requires the prosecution to lay a foundation establishing the accuracy of the breath test before the result may be admitted as evidence.

Part of this foundation includes proof that the chemicals used in the test were of the proper kind and mixed in the proper proportions.

This requirement is usually accomplished through documentation establishing that the simulator solution was separately tested and found to contain the appropriate amount of alcohol.

The simulator solution and the ethyl alcohol used to test the gas chromatograph are both provided by outside agencies.

Unlike the simulator solution, however, the ethyl alcohol used in the blood test is rarely tested to establish that it is “pure” as claimed by the manufacture.

This is an issue an experienced DWI lawyer may explore when defending against the blood test at trial.

If you have been arrested for DWI and need legal help, call us at 585-484-7432.