Do breath tests really underestimate blood alcohol concentration?

It has been reported that in the fully postabsorptive state, breath test results underestimate actual blood alcohol concentration (BAC) in 86% of the population. Reanalysis of the data on which this conclusion was based indicates 77% of these subjects were actually underestimated, and 23% were overestimated. Further refinements indicate 68% had their actual BAC underestimated, 16% were acceptably close to the actual BAC, and 16% were overestimated. Perhaps more importantly, comparison of this data with other results indicates fully postabsorptive status may not occur until more than three hours after drinking. Consequently, breath test results may tend to overestimate actual BAC for significant amounts of time after the peak BAC has been reached.