Historical events leading to the development of the first handheld instrument for breath alcohol analysis using an electrochemical sensor are reviewed. The first prototype instrument, known as the Alcolmeter Pocket Model, became available in 1972 and weighed only 180 g and was about the size of a cellphone. By the mid-1970s, the Alcolmeter instrument was used by police forces in several countries as a preliminary roadside test of driver sobriety. Positive results in a roadside breath test were considered sufficient evidence to arrest a suspect for further evaluation and testing. This might entail an evidential-quality breath alcohol test or taking a sample of the driver's blood for analysis at a forensic laboratory. The main advantages of breath testing over blood testing are the non-invasive nature of the sampling procedure compared with sticking a needle in a vein to draw blood, and obtaining immediate information whether or not a person is in breach of the drunk driving legislation.