Do wrist locks work?

Are the techniques demonstrated in this video really effective in reality? Do they work in "the street"?

The short answer is yes:

"I myself was put into a wrist lock like I have never experienced before - I was screaming in pain"

- Occupy Sydney protester

But it's not that simple.

While I was working as a security guard on the sunshine coast, a young man of about 18 years who had been asked to leave was becoming a bit hysterical. He was drunk, refused to go and was threatening myself and the other guard, and dared us to hit him. The other guard touched the kid's elbow in a "come this way" gesture, and his hand was slapped away.

The situation was escalating, so I took him down. He was surprisingly strong, but I had him restrained. He was face down while I sat on his back.

The other guard tried to assist by applying a wrist lock. This was unnecessary as everything was under control and there was no need to cause the kid any pain at this stage.

In any case, the wrist lock didn't work. He simply made a fist and writhed his arm around. This chap was face down with two people controlling him, yet it wasn't possible to lock up his hand and wrist.

If it doesn't work on someone face down with their arm pulled behind their back, it's not going to work so well on someone who is standing up and and fighting you. I've heard the expression "chasing butterflies" in reference to wrist locks before, and that's exactly what it looks like when someone is trying to pluck a wrist out of the air.

This is why we don't see these techniques applied in MMA. We might see it happen one day, but wrist locking professional fighters is difficult to the point that very few fighters train them. It's incredibly low-percentage.

Having said that, on protesters who want to make a point about being non-violent, and who would like to demonstrate to the world how brutal police are, it'll work just fine. Let's say someone is sitting there, refusing to move, but they're non-combative and dragging them away might not be an option. This might be the ideal situation for a wrist lock to be applied. So in some limited situations they can be useful, and I'm not against training them at all. In fact, I think that it's good to have them in your toolbox.

This is my favourite example of a wrist lock being applied against a fully resisting, experienced opponent - performed by BJJ legend, Jacare:

You might notice that it looks nothing like the kind of wrist attacks you see demonstrated in most videos. Jacare is actually holding the elbow and locking the wrist against his own chest as his opponent does a lapel grab. It does not involve grabbing the hand or wrist at all.

I will also say this: wrist locks are usually taught to be applied to a standing opponent. But it's much easier to apply them when you have a dominant position on the ground.