The legal blood alcohol concentration (BAC) limit was established so that courts could measure a level of intoxication against the risk of a motorist’s impairment. If someone reaches this level, the court can reliably presume that they were impaired while driving. This takes some bias out of the equation. Drivers will sometimes claim that they weren’t actually impaired, regardless of the breath test results, so the court uses the legal limit as a way to define per se intoxication.
This does not mean that a driver can’t get arrested even if their BAC is under the legal limit. In some cases, police officers will see other evidence of impairment that allegedly warrants an arrest. But it is still important to know what the limit is, and the truth is that it varies, depending on what type of driver someone is.
The standard limit
Most drivers have the same standard limit of a blood alcohol concentration of 0.08%. This is true in Louisiana and many other states. It is the number that is going to be cited in the vast majority of drunk driving cases. This usually means that most adults can have a drink or two before they will reach this limit.
The commercial limit
However, commercial drivers have to be careful about drinking anything before they get behind the wheel. They have a lower legal limit of just 0.04%. This is due to the heightened obligation that they have to ensure that the roads are safe for others. Commercial drivers have oversized “common carrier” vehicles that can cause serious injuries in an accident, so they are also held to a higher standard.
The underage limit
Finally, drivers who are under 21 years old have their own limit. It is set at just 0.02%. This is so insignificant that a driver could reach that level without even having an entire drink. The basis for this law is simply the idea that someone who is under 21 shouldn’t have been drinking any alcohol because they are too young to legally do so.
Legal defense options
As can be seen, the issue of “the” legal limit is not quite as simple as most people assume. Similarly, defending against impaired driving charges is not always straightforward either. As a result, seeking legal guidance as proactively as possible is usually a good idea.