In places like the United Kingdom, a hip flask defence is a defence to an allegation of drink driving that a driver had consumed alcohol between the time of a vehicular offence, such as a traffic collision, and a breathalyser test, so that a positive result does not actually indicate that they were driving while intoxicated.[1][2]

Though popular (in 1991, the defence was used in 90% of Swedish appeals against drink driving convictions),[3] the hip flask defence is not always effective. It is possible to back calculate the amount of alcohol and prove an offence nevertheless.[4]


  1. ^ "What is a hipflask defence?". Motoring Law. 24 October 2016. Retrieved 26 May 2020.
  2. ^ "Drink Drive & Drunk Driving Solicitors Devon, Somerset & Dorset". Slee Blackwell. 8 May 2017. Retrieved 26 May 2020.
  3. ^ Jones, AW (July 1991). "Top ten defence challenges among drinking drivers in Sweden". Medicine, Science, and the Law. 31 (3): 229–38. doi:10.1177/002580249103100307. PMID 1822585. S2CID 8346436.
  4. ^ Iffland, R; AW Jones (2002). "Evaluating alleged drinking after driving: the hip-flask defence: Part 1. Double blood samples and urine-to-blood alcohol relationship". Medicine, Science, and the Law. 42 (3): 207–224. doi:10.1177/002580240204200305. PMID 12201066. S2CID 22197478. Retrieved 25 April 2009.