If one witness says 18 mph and another says 28 mph, that is not reasonable doubt, it is some doubt. The reasonable comes into play when the jurors have to decide which witness is more credible. They do not have to be completely certain and can have some doubt.
If two witnesses say the opposite thing and that is called reasonable doubt, then no one would ever be convicted. Juries have to decide which witnesses' testimony is beyond mere doubt, but to a higher level of certainty but not absolute certainty.
I was on a drunk driving trial a few years ago and after much deliberation one woman still would not convict because she misunderstood the directions. She thought the defendent had to be drop dead drunk to be convicted. When the judge explained .... enough to drink to be impaired, she immediately voted to convict as she felt that one drink was enough to be impaired.
Erica said she had 3 drinks over a period of a few hours. In order to have a BAC of a .15% a 140lb female has had 4 drinks in an hour.
I agree with jeffk, she was legally drunk, nearly twice the legal limit. If you are interested read on about the effects of alcohol at various BAC levels. Erica's level is in red.
I don't know why juries feel sorry for drunk drivers and have trouble convicting.
Otherwise... lets do the no rain dance!!
BAL .02 %-.03 %: You feel mildly relaxed and maybe a little lightheaded. Your inhibitions are slightly loosened, and whatever mood you were in before you started drinking may be mildly intensified.
BAL .05 %-.06 %: You feel warm and relaxed. If you're the shy type when you're sober, you lose your feelings of shyness. Your behavior may become exaggerated, making you talk louder or faster or act bolder than usual. Emotions are intensified, so your good moods are better and your bad moods are worse. You may also feel a mild sense of euphoria.
BAL .08 %-.09 %: You believe you're functioning better than you actually are. At this level, you may start to slur your speech. Your sense of balance is probably off, and your motor skills are starting to become impaired. Your ability to see and hear clearly is diminished. Your judgment is being affected, so it's difficult for you to decide whether or not to continue drinking. Your ability to evaluate sexual situations is impaired. Students may jokingly refer to this state of mind as beer goggles, but this BAL can have serious repercussions.
BAL .10 %-.12 %: At this level, you feel euphoric, but you lack coordination and balance. Your motor skills are markedly impaired, as are your judgment and memory. You probably don't remember how many drinks you've had. Your emotions are exaggerated, and some people become loud, aggressive, or belligerent. If you're a guy, you may have trouble getting an erection when your BAL is this high.
BAL .14 %-.17 %: Your euphoric feelings may give way to unpleasant feelings. You have difficulty talking, walking, or even standing. Your judgment and perception are severely impaired. You may become more aggressive, and there is an increased risk of accidentally injuring yourself or others. This is the point when you may experience a blackout.
BAL .20 %: You feel confused, dazed, or otherwise disoriented. You need help to stand up or walk. If you hurt yourself at this point, you probably won't realize it because you won't feel pain. If you are aware You've injured yourself, chances are you won't do anything about it. At this point you may experience nausea and/or start vomiting (keep in mind that for some people, a lower blood alcohol level than .20 % may cause vomiting). Your gag reflex is impaired, so you could choke if you do throw up. Since blackouts are likely at this level, you may not remember any of this.
...there is more, but you get the picture.