I was on a jury for a DUI case a few years ago. The young woman (below the legal age in fact) claimed to have had only one beer at an office Christmas party but registered .10 on the breath analysis machine.
The prosecution had the State Patrol officer who maintained the machine testify. He'd obviously done this before and was very well prepared with detailed charts showing how the machine worked and was calibrated.
The girl's public defender said the machine must have been wrong but offered no evidence to support that contention, other than her testimony that she had only the one beer. We felt sorry about convicting her.
About three months later every conviction based on evidence from that particular machine was thrown out by the state supreme court!
Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.