When confronted with a cop or any other 'agent' demanding you do something:

You: Are you ordering me to produce a drivers license and registration?

Cop: Yes. That is an order. 

You: Ah! I love filling orders for His Majesty. I'm here to provide products and services for His Majesty. I love orders. I'm going to require x amount of money up front and a liability waiver before I do that for insurance purposes.

- Don't do anything until you're paid. -

You: I require payment up front. Are you going to confess to enslaving me by forcing me, compelling me, to perform services for His Majesty for free? There's laws against that though I'd love to do something for you right now but I really need to be paid because, well, I got this religious belief that I need to eat and the only way I can eat is if I buy food and the only way I can do that is if I get paid for services that I provide his majesty, unless you're enslaving me. Because if you're just going to force me to do it I can't wait to go to court because I'm going to demand the money once I get there, I'm not going to do a fucking thing until I get paid, but I'm going to testify that you wouldn't pay me or agree to pay me. You just tried to force me to work for free.

The four or five words:
NEED COMPENSATION, AND LIABILITY WAIVER/NO SLAVERY (you can choose which to say)

