On Thursday, the Supreme Court of Kentucky ruled that a man can only be convicted of drunk driving if the evidence shows he was actually drunk at the time he was driving.

In 2003, a Fayette District Court sentenced Nelson Lopez to 21 days in jail (reduced to 10 days) and a $500 fine when a breath test showed a blood alcohol level of 0.08 two hours after his arrest. At trial, prosecutors argued that the jury had no choice but to convict Lopez based solely on this evidence, regardless of what his blood alcohol level was at the time he was driving.

Fred Peters, the attorney representing Lopez, argued on appeal that this interpretation of the law was absurd. If someone breaks down on the highway and has a drink while waiting for assistance, he could be convicted of drunk driving despite the lack of any evidence that he was anything but perfectly sober while he operated the vehicle. Similarly, a person arrested for rowdy conduct at a bar could be charged with drunk driving if the prosecution merely proved that he drove to the bar.

The Washington Post recently documented cases in Washington, DC where perfectly sober individuals were arrested for drunk driving. Each was told they had to pay $400 in "counseling fees" for the charges to be dropped.

Peters also argued that because it takes 60-90 minutes for alcohol to be absorbed in the blood stream, a blood test while driving could read lower than a test taken two hours later.

The court agreed that these factors must be considered and ordered a retrial for Lopez.

"The prosecutor should not have been permitted to tell the jury that appellant's blood alcohol concentration did not have to be 0.08 or more at the time he was operating his motor vehicle so long as it was at that level when the test was administered," the unanimous court concluded.

The full text of the ruling is available below in a 530k PDF document.