I find the Austrian School of Economics really interesting.
Particularly books written by American economist Murray Rothbard, who talks about free markets, government (particularly government intervention) and inflation.
There's a very short book you can read called "What has Government Done to Our Money?”
Through consent. The guy probably either has terminal illness and is happy to contribute to research or is completely paralysed, that an operation like this could benefit both parties.
It's an agreement and I'm sure the risks are expressed to the individual.