Montana's drunk driving enforcement rates as the worst in the nation, while five other states have the most robust enforcement in the nation, according to a report from Mothers Against Drunk Driving (MADD).

The Jan. 24 report rated every state's drunk driving enforcement using a scale of one to five stars. Montana earned just a half-star, and five additional lowest-ranking states — Idaho, Iowa, Rhode Island, South Dakota and Wyoming — scored 1.5 stars.

While no state earned a perfect score, five top-ranking states received 4.5 stars. These included Arizona, Maryland, Mississippi, Nevada, and West Virginia.

The report rates state enforcement of drunk driving in five categories:

• Conducting sobriety checkpoints

• Ignition interlocks for all drunk driving offenders with a .08 blood alcohol concentration (BAC) and above

• Administratively revoking driving privileges upon arrest for drunk driving

• Creating enhanced penalties for those who drive drunk with children in the vehicle

• Adopting penalties and expediting warrants for suspected drunk drivers who refuse an alcohol test.

Some noteworthy data in the report includes:

• 30 states and the District of Columbia require ignition interlocks after the first offense.

• 37 states and the District of Columbia conduct sobriety checkpoints — with 32 and the District of Columbia conducting them at least once a month.

• 41 states and the District of Columbia immediately revoke driving privileges while the offender awaits trial.

• 47 states and the District of Columbia have additional penalties for driving drunk with a child passenger, but only 7 states treat this crime as a felony.

The new report, which also highlights drunk driving countermeasures, is part of MADD's Campaign to Eliminate Drunk Driving. Launched in 2006, the campaign has helped to reduce drunk driving deaths by 23.5%, according to Colleen Sheehey-Church, national president of MADD. 

Over 10,000 people still lose their lives every year to drunk driving. After years of steady decline, drunk driving deaths increased in 2015 and 2016.

To motivate states to strengthen their drunk driving laws, MADD’s rating system allows for half-star ratings for states that need to improve their existing laws. For example, the states that conduct sobriety checkpoints receive a half star, but those that conduct them at least once a month receive a full star.

Over the past year, MADD’s campaign efforts have helped pass and strengthen ignition interlock laws in Nevada, Oklahoma, Texas, Kansas, and Oregon. The organization also successfully curbed attempts to weaken current interlock laws in Arkansas, Texas, Wyoming, Kansas, Virginia, Georgia, and Connecticut.

Read the report here.