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What is Presumptive Impairment?

Depending on whose statistics you wish to cite, drivers who are impaired by alcohol at the time of an accident are responsible for between 10,000 and 13,000 traffic fatalities each year. In today’s post, the personal injury lawyer at the Doan Law Firm will discuss the concept of “presumptive impairment” and how it relates to lawsuits alleging personal injury and wrongful death.


For states to receive certain types of funding through the federal Department of Transportation or one of its administrative divisions, each state must have a law “on the books” which gives that state’s legal definition of Driving While Impaired / Driving While Intoxicated. In all states, a blood alcohol concentration (BAC) of 0.08% or greater is taken to be proof that that a driver’s judgment and/or reflexes were impaired at the time an accident occurred. If a state law holds that a BAC of greater than 0.08% is sufficient to convict a driver of the crime of Driving While Impaired, regardless of any other evidence to the contrary, that state’s law is said to allow a conviction based on a “presumption of impairment.”

Liability and presumptive impairment

The legal basis for assigning liability in presumptive impairment begins from a position that a reasonably-prudent individual, being aware that driving while impaired poses a risk to others, would not willingly operate a motor vehicle while in such a condition. Therefore, by operating a vehicle while impaired, that driver has acted with deliberate disregard for the health and safety of others and thus has met the legal definition of negligence.

As opposed to criminal law, where all the available evidence must support a conviction, civil law requires only that the evidence be sufficient to suggest that negligence has occurred and that such negligence was the direct cause of an injury. In the case of an allegedly-impaired driver, this means that a driver whose BAC is greater than 0.08% is assumed to have been impaired based on his or her BAC alone and is therefore liable for damages. However, while a BAC in excess of 0.08% is considered sufficient to convict in a criminal court, it is not sufficient to assign liability for damages in a civil lawsuit.

In law, the question of liability is usually determined by a jury (or by a judge if allowed by state law). Hence, the available facts surrounding an injury must be taken together before liability can be determined and the appropriate amount of damages to be paid is decided. If, for example, a jury determines that an impaired driver was responsible for an accident but that the injured party’s own actions contributed to his or her injuries, the doctrine of “comparative” or “contributory” may come into play and could result in the amount of damages to paid being reduced by an amount that reflects the injured party’s “degree of fault.” In some jurisdictions, the extent of the injured party’s contributory negligence can actually result in an inability to recover damages in a civil lawsuit.

Why you need a personal injury and accident lawyer in presumptive impairment accidents

If a driver is found to be at fault in an accident, and that driver is found to have alcohol in his or her system, the issue of liability for damages is often obvious and an out-of-court agreement can often be negotiated. In fact, many impaired driver cases are settled in this manner. At other times, particularly when the at-fault driver’s BAC is less than 0.08% or if the injured party also tests positive for alcohol, questions of comparative negligence will usually result in the matter being submitted to a jury.

In many states a BAC of 0.08% is all that is necessary to convict a driver on a criminal charge of Driving While Impaired. However, this does not mean that 0.08% is some “magic number” such that anything less than 0.08% is “proof” that a driver was not impaired at the time of an accident. In such cases, other evidence such as the results of a field sobriety test or statements taken from witnesses must be considered when considering the degree of impairment.

In closing, and since impaired driver cases are usually more complex than they may appear at first glance, it is vital that anyone injured in an impaired driver accident retain the services of an experienced personal injury attorney in order to protect their legal right to receive compensation for their injuries and/or property losses.

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