Drunk drivers who find themselves in trouble with the law have a new legal resource at their fingertips. Seattle-based Avvo has introduced a new iPhone application that not only calculates one's blood alcohol level (suggesting numbers for local cab companies if you exceed the legal limit) but offers recommendations for DUI lawyers if you happen to get pulled over by the police.

Dubbed "Last Call," the app lets users log the number of drinks they consume during a set period.  It measures those drinks -- whether beer, wine or a cocktail -- against a person's gender and weight. If the blood alcohol level exceeds the legal limit, the "Last Call" service offers numbers for local cab companies. If a person doesn't heed the advice and they subsequently get pulled over,  the application suggests the top DUI lawyers in the area from the Avvo legal directory.

"Last Call is awesome because on the front end we can help you understand where you are in your alcohol absorption," said Avvo CEO Mark Britton. "But, secondarily, if you have drunk too much and you need a taxi on the one hand or you have been picked up and need a DUI lawyer, you can get both of those in real time."

Justin Weiss and some of the other Avvo developers started kicking around the idea in their spare time after recognizing that DUIs represented one of the most-searched terms in the company's lawyer directory. Weiss said they tested the system at a number of local pubs, calibrating the "Last Call" tool against a Breathalyzer.

"It was actually pretty accurate," said Weiss.  "As a general idea of how close you are to the legal limit, I think it is a great tool." (Thankfully, they didn't have to use the call a lawyer function). Weiss said they used standard algorithms from DUI lawyers to determine one's blood alcohol level.

When a drinker reaches the .08 percent blood alcohol level, a line turns red as do numbers in the application.

It took some time for the application to receive approval, with Britton saying that Apple's legal counsel took a close look at "Last Call." 

Avvo could be opening itself up to potential legal issues, but Britton said they put the proper disclaimers in place. A description of the service in the iPhone store says that "Last Call is provided for entertainment purposes only."

"I think the biggest legal issue is people driving drunk and the beauty of this tool is that it keeps them away from that," said Britton. "This is like any tool that is there to help you understand the law.... As long as we are helping people, any minor risk is far outweighed by the return."

In a recent TV spot, Apple boasted that the iPhone is "solving life's dilemmas one app at a time." Facing a drunk driving charge certainly would qualify.