Operating any vehicle on public roads requires more than just driving skills. It needs the driver to maintain proper energy and concentration levels so that he or she can drive for as long as needed without becoming insensitive to what's happening on the road with other vehicles or pedestrians. Driving under the influence of either alcohol or narcotic substances can impair a driver's abilities and drunk drivers are therefore strictly penalized by state and federal laws.
In Montana, for instance, a driver aged over 21 whose blood alcohol concentration is above the mandated threshold value of 0.08 can be charged with a violation, even if this does not actually prevent him or her from driving reasonably without impairment. For drivers who operate commercial trucks or delivery vehicles, this threshold is even lower, at 0.04 while, for drivers younger than 21 years of age, the BAC threshold is 0.02.
Even a first conviction for a DUI or BAC offense can result in both jail time and monetary penalties, with the driver likely to spend up to six months in prison, in addition to paying a fine of up to $1,000. Further, the person's driver's license may also be suspended for up to six months. During this period, the court may allow the person to drive using a restricted probationary license which limits the privilege to drive to specific trips, and may also require using ignition interlock devices.
Most crucially, such a conviction affects a person's driving record, and repeat offenders can find their driving privileges completely rescinded. In Montana, a repeat offender is someone who gets convicted twice within a 10-year period. If a person is convicted over four times, he or she is charged with a felony offense.