So one of the things I particularly looked at was the use of O.C. spray, oleoresin capsicum spray, pepper spray, by Australian police and seeing when that had been introduced, what had happened and those sorts of issues.

So you've got traditional things like pepper spray, O.C. spray up at the top there, or Tasers over here.

Now when they introduced O.C. spray in Queensland, they were really explicit.

They're not obeying the directions that we're giving them, so we'll give them a shot of the O.C. spray.

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And the red arrow represents the point where Queensland actually said, Yes, this is where we're going to give all police officers across the entire state access to O.C. spray.

Anyone want to take a stab at the number of times, given how they've introduced this, the number of times police in Queensland used O.C. spray in that period?

I'm going to go out on a limb here and say that if Queensland police didn't have O.C. spray, they wouldn't have shot 2,226 people in those two years.

And one study that I found, a particularly interesting one, was actually in Queensland, because they had a trial period for the use of pepper spray before they actually introduced it more broadly.

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In fact, if you have a look at the studies that they were looking at, the material they were collecting and examining, you can see the suspects were only armed in about 15 percent of cases where O.C. spray was used.

Pepper spray and tasers are in increasing use by both police and military, and more exotic non lethal weapons such as heat rays are in the works. At TEDxCanberra, ethicist Stephen Coleman explores the unexpected consequences of their introduction and asks some challenging questions.