Hip flask defence

The hip flask defence, also known as the rising blood alcohol defence, is a defence to a charge of drink driving based upon the claim that the driver consumed alcohol between the time of a vehicular offence, such as a traffic collision, and the time of administration of a test for intoxication such as a breathalyser test. The defense asserts that the driver was not intoxicated at the time that they were driving, but had a higher blood alcohol level at the time of the test due to that subsequent consumption of alcohol.^[1][2]

The defence is not necessarily successful, both because it may not be believed by a jury or other finder of fact,^[3] or may be disproved based upon the analysis of the amount of alcohol claimed to have been consumed after the driver stopped operating the vehicle.^[4][5]