You point out that police officers have no way of diagnosing people with mental illness, which is true. Plenty of people with mental illness are on their own, some medicated and some not, but they do have driver's licenses. Someone who is mentally disabled may not be in this category, but it depends on their ability to demonstrate driving skills and take the test. We thus have the possibility of a taser being used on an autistic individual, who while not deliberately belligerent can be non-responsive and seem uncooperative.

Tazing causes injuries, and have been implicated in cardiac incidents and in deaths as well. Please take a look at this article from the CBC.

As police have no way of diagnosing mental illness in a person pulled over on a speeding violation, likewise officers can't tell by looking who has a pacemaker. The taser is designed "to induce incapacitation from involuntary muscle contraction."

Practicing physicians confronted with a subject who has been subdued with a TASER will likely be concerned about that patient's risk for cardiac arrhythmia. It is important to understand that the TASER is a weapon, not a medical device, and hence not subject to FDA regulation. (It is also not regulated by the Consumer Product Safety Commission, having been classified by the Bureau of Alcohol, Tobacco, and Firearms as a firearm and thus not within the CPSC's purview.)

(Both quotes from the American College of Emergency Physicians article on treating taser injuries.)

For this reason alone, the use of a taser on an elderly person who is not physically violent ought to be avoided like the plague.

Nowhere in this thread has anyone said that the woman should have been let go scot free, only that the use of the taser was an extreme reaction by a law enforcement officer in the circumstances. She did, in fact, agree to sign the ticket (in an insulting way, yes, but she agreed) before he tazed her. That's what did it for me. If she had physically attacked him or displayed anything that might have been used as a weapon, besides her howitzer of a mouth, my reaction would have been different as well, but she didn't.

I thought that the taser was to be used to subdue violent resistors as a safer alternative to shooting them or engaging in hand-to-hand combat. I have never thought the taser was to be used on mouthy and uncooperative people who present no other threat in order to make them more, um, docile and teach them manners. If I'm wrong about this and tasers are routinely used in this way, then I see I will have to work on getting tasers removed from the accepted weapons of choice available to the police until such time as they receive more training in acceptable use. I expect police officers to be able to protect themselves. That doesn't extend to inflicting injury on someone who is obnoxious but not violent.