In a drink driving prosecution, the entire case against you rests on a single, crucial piece of evidence: a number. This number—the reading from an evidential breathalyser or the result of a blood or urine analysis—can seem like an irrefutable scientific fact. However, this "fact" is the end product of a complex chain of technology, scientific procedure, and forensic analysis, and...

In a drink driving prosecution, the evidence can seem overwhelming. A positive breath test, a police officer's statement—it is easy to believe that the case is an open-and-shut matter. However, the law demands an incredibly high standard of procedural perfection from the police. The entire case is a chain of evidence, and if a single link in that chain is broken by a procedural error, the...