Regular nets are too bulky and easy to cut through, while nanowire nets can cause some pretty freakish cuts, especially if the person keeps struggling. Plus, OK, you get 20 cops in nets before you run out, they just call for backup and get 20 more, not that they'd really have to because they'd have all the time in the world to get out of those nets.
Inflatability is the greatest nanotech advent that I can think of. When you pufferfish into a huge object that's way bigger than a police cruiser, there's just simply nothing they can do to arrest you - they can't even claim that you've attacked them, you just sucked in a lot of air in several seconds, still slowly enough to walk away from you as you expand. Those inflatable tubes (aka pufferfish / porcupine suit "pricks") will require up to 100 tons of pressure per square inch to penetrate them, tens of times more than regular firearms can deliver. They can wait you out, but you can have a backpack full of food and water, and in the meantime you can watch hundreds of cops trying to wrestle their way through your giant inflated pricks and debate if they should try to get a bunch of bulldozers together so they could try to move you that way.
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Or, if you forget to press a inflate button (which can be made to be accessible while in handcuffs or even a dental implant) before they get you into the police cruiser / patty wagon, you can always try to do something like this:
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You can of course hurt yourself and others when inflating in a confined space, so we'll probably need various inflation speed settings, separate controls for pricks on different parts of the body, a pressure-sensitive safety feature, and of course emergency release...