Salt Lake City police officers carry more than just their identification when they go to a social event.

They carry the business card of Police Chief Chris Burbank, which also lists the phone numbers of taxi companies. If officers have been drinking, Burbank encourages them to call a cab. He'll pick up the tab and the tip. That's just one example of what police across the country are doing to stem the toll of law enforcement personnel who drink and then get behind the wheel, sometimes with tragic results.

The case of a Linden, N.J., police officer who had two arrests for drunk driving and was behind the wheel in a fatal wrong-way crash last month was an extreme example of that toll, a researcher of police behavior tells NJ.com .

A survey of police drunk-driving incidents and academic research shows a patchwork effort to tackle the problem: Some departments offer no room for a second chance, while others are more lenient. The extent of the problem is not known since state and federal agencies do not track drunk-driving incidents involving police.

Some departments, such as the Los Angeles Police Department, in recent years have told officers convicted of drunk driving charges that they have to sign a contract promising to stay sober and seek professional help if they want to keep their job, according to a 2012 Police Executive Research Forum article.