Tweaking DWI law

A new law is designed to close a loophole that enabled people arrested for driving while intoxicated to challenge the blood test. The previous law adopted in 1982 required the use of alcohol-free antiseptic to cleanse the skin before the blood is drawn. Drunken-driving charges could be dismissed if the testing guidelines were not followed.

The most famous case involved state Rep. Charles Portwood of Ballwin. His drunken-driving charge was thrown out in 2006 because a hospital nurse had used the wrong kind of swab when administering a blood test two hours earlier. Two hours after the accident, the alcohol level in Portwood's blood was more than twice the legal limit.

Portwood pleaded guilty to leaving the scene of an accident. His case provided the impetus for changing the law.

Defense attorneys viewed the previous proscription against using alcohol-based antiseptics as a safeguard against false positives. But Cape Girardeau County Prosecuting Attorney Morley Swingle says the presence of alcohol in the antiseptic has been shown by studies to make no difference in the result of the test. Isopropyl alcohol is used for swabs. Blood tests detect ethanol, the alcohol in liquor.

This is an instance of updating a law to correspond with good science.