How do the police measure the level of alcohol in your body? ?

What are the different ways that blood alcohol concentration can be measured?  Most of the time the officer is going to request that you provide a breath sample, but they may also request blood or urine.  There are two different times that an officer may request a breath sample.  First, the officer has a hand-held device that can take a breath sample and provide an analysis of blood alcohol content.  The problem is that by law this device is not reliable so they will always request that you provide another breath sample at the police station on another machine which is considered to be more reliable than the hand-held device.  Don’t be fooled- this device also has problems.  Even if a person where to provide a sample each of their breath, blood and urine, all three would have a different alcohol level.  There are many factors to determining the level of blood alcohol concentration and the time of vehicle operation.  Some states do not allow alcohol measurement through urine because it is so unreliable.  In order to obtain more convictions regardless of the reliability of this test, Iowa still allows urine testing.  You always have the right to make a reasonable number of phone calls prior to making a decision on whether to provide a sample for testing.