>>Can an American Pruner help?
In the UK, a 'roadside' breath-test simply shows positive or negative. If positive, a driver is arrested and taken to a police where he provides a specimen of breath to a machine which almost instantly gives the precise proportion of alcohol.
Does that system and procedure exist in America?
Or are all alcohol proportions measured by analysis of a blood or urine sample?<<
In the U.S. driver alcohol testing procedures vary from state to state. Here's a lawyer's site with advice on local procedures and how to beat the rap:
http://www.drunkdrivingdefense.com/g...eath-tests.htm
The federal procedure for testing pilots is described here:
http://www.aviationmedicine.com/DOTetohtest.htm