New York, April 7 (IANS): Increasing punishments for taking the wheel after excess drinking reduces the likelihood of repeat offences, says a new study.

"I think we might see even greater benefits if we were to increase the sanctions or punishments more steeply," said study author Benjamin Hansen from the University of Oregon in the US.

The researcher found that lowering the legal blood alcohol content (BAC) threshold further discourages drunk driving. The study is based on data gathered from 1999 to 2011 in the state of Washington.

BAC is the concentration of alcohol within a person's blood stream. It refers to how much alcohol is present in 100 millilitres of blood.

In Washington, a BAC over .08 percent is considered to be driving under the influence. The average drunk driver involved in a fatality had BACs at least two times the legal limit, Hansen noted.

"These drivers are the most costly. In terms of fatality risk, a person with a BAC of .15 is about 20-30 times more dangerous than a person who is sober," Hansen pointed out.

Lowering the BAC threshold, he wrote in the study, might make drivers "internalise the external costs of drunk driving."

The findings appeared in the journal American Economic Review.