THE POLICE PROBLEM

I had a wee look at DUI laws in Tennessee, where this happened, and a DUI has far more severe penalties than reckless driving. Plus, based on the info on the article, I don't even know if what was described would count as reckless driving (one of the examples given was doing a wheelie on a motor cycle), so I am wondering whether the DUI charge was because the level of driving wasn't to the level that they could be charged for reckless driving, so he went for a DUI instead. This is speculation though, because we know that the officer wrote that "[the driver] crossed over lanes twice", and that could describe a wide range of driving.

It could, for example, describe someone who drifts a tire's width out of their lane, on a road where road markings are poor and there is little other traffic. Doing that twice wouldn't be great (and may be indicative of driver fatigue), but it certainly wouldn't warrant an arrest. Like I say, insufficient info means that this is speculation, but it is striking to me that they didn't try to charge her with reckless driving after the blood test came up clear. If this driver was driving badly, but not dangerously, then they shouldn't have been arrested.

I think you make a few undue assumptions in your comment that are unreasonable and possibly why so many have downvoted you (and I hope that said downvotes won't cause you to ignore people replying with good faith criticism): 1.) You assume that the level of driving she was pulled over for was dangerous enough to be at risk of harming someone, but we don't know that. In addition to the point I made above about her driving seemingly not being enough to count as "reckless driving", I also want to highlight that bad or dangerous driving isn't a prerequisite for a DUI; where I live, police occasionally do spot checks of drivers at night time in high-DUI areas (I've been pulled over and breathalysed a few times on a particular stretch of road, just for driving late at night), and if someone was driving perfectly but was above the legal limit for alcohol, then that's enough to arrest them. I make this point to emphasise that DUI != Dangerous driving, and that we shouldn't conflate the two. If she was driving dangerously whilst not intoxicated, then there are laws intended to penalise that, and so she shouldn't have been charged with a DUI regardless. Penalties for DUIs are typically harsher too, which is why the article highlights the mandatory loss of license for what should have probably just been a slap on the wrist, if that.

2.) You make assumptions about the nature of the medication being prescribed. Xanax is indeed, a medication that is prescribed for anxiety, and it can be (depending on the dose and the person) be quite highly sedating, but by the sounds of your comment, you haven't considered the possibility that the medication(s) she was prescribed may not be sedating at all. For example, atomoxetine is an ADHD medication that's an SNRI, a class of medications that are used to medicate depression and/or anxiety; I know a few people who have been prescribed it due to having comorbid anxiety and ADHD. That's just one example of medication that may have been detected but would be unlikely to impact a person's ability to drive safely. Even if the driver were prescribed a benzodiazepine (such as Xanax), that doesn't mean it was sedating enough to affect her driving. Whether a medication is likely to affect your driving is a discussion between you and your doctor, and even if we assume the person was driving dangerously, we have no reason to assume her medication is at all relevant.

I also take medication for ADHD and anxiety, and they're not the kind of meds that impact ability to drive. If I were driving dangerously (to the degree that I was a risk to other road users), I hope I would be pulled over before I could cause harm, and that would likely warrant me being arrested, but I don't think I should be charged with a DUI in that scenario — not least of all because if we cast too wide a net for what counts as DUI, then it sort of depowers the category. Morally speaking, people tend to view driving under the influence far more harshly than other kinds of bad or irresponsible driving, and rightly so, in my view. It's a hard line that I have always been cautious to never cross, and I would be disgusted if someone I knew had. Unequivocally, the person in the article should not have been charged with DUI, even if they had been driving recklessly (which again, we don't know whether they were).

I hope my comment doesn't come across like I'm hating on you, because whilst I was shocked at your comment, I only wrote all this because I hoped we could have a productive discussion. I'd be interested to hear if you have any thoughts in response to my comment, even if I haven't changed your opinion.