Tasers had been discharged 30 times since they were rolled out nationally, and in all but four cases their use had been successful. They were also discharged 16 times during initial trials, two of which were unsuccessful.[LINK]
See also [LINK], [LINK], and [LINK].
That's a consistent 13% rate of deployment failure. Other reports have the failure rate at about twice that level. In any case, it's a very significant rate.
Deployment failures often represent an escalation that goes badly wrong. Deployment failures endanger the lives of everyone involved (one recent failed taser deployment in New Zealand resulted in two officers being shot, nearly killed). And that's just the negative consequences of these acknowledged failures, let alone the overuse, misuse and abuse.
Considering that tasers are used many, many, many times more often than police would have historically used bullets, it's obvious that the moral negatives are at least on the same order of magnitude as any moral positives.
Next consider that the moral negatives are randomly distributed among those that often do not deserve them. And consider the risk of DEATH by taser (claims that the risk of DEATH by taser is zero, or essentially zero, are false advertising, deceptive marketing and dangerously incorrect).
It seems perfectly clear that an outright moratorium would be safer moral ground than the present all-too-typical overuse, misuse and abuse.
And even if you wish to believe that tasers can bring occasional positive benefits, you'd logically be forced to accept the very tight restrictions of the sort recommended by the Canadian Braidwood Inquiry.
In the Canadian province of British Columbia, that equates to a reported 91% drop in taser use. Not a bad start.
This sort of moral mathematics is perfectly obvious.
Police mindlessly defending tasers is probably a sign that the stun gun salesmen have infiltrated the ranks. An unbiased decision maker would acknowledge the moral balancing act, and not wait until a national incident forces an expensive inquiry.
Learn the lessons from Canada (Braidwood Inquiry).