The UK sometimes has anti drink-driving campaigns. Police forces increase the number of breathalyser tests. They're only allowed to use a breathalyser if they have reason to suspect someone is drunk - they saw them leaving a pub or driving erratically.
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> • During 2009, there were 813,288 screening breath tests carried out. This is a 14 per cent increase from 711,658 in 2008. This increase coincides with the introduction of new digital recording equipment, which may have streamlined breath test procedures for many forces.
> • The number of positive or refused tests in 2009 increased by three per cent from 91,666 in 2008 to 93,973 in 2009 after a three year decline.
> • The proportion of tests that were positive or refused in 2009 was 12 per cent, one percentage point lower than in 2008.
It seems that traffic officers come into contact with very many people who they think are criminals but who are not criminals.