Further, most state laws would preclude an attorney from representing someone for a piece of the pie that is not roughly the same as his fees and the like. So, I can not accept a car worth $30k in exchange for a simple will, it is against the ethics rules for me to do so.
This is an interesting point that I haven't seen raised in patents before. But I think it can be easily ignored in the context of taking a piece of the proceeds of a patent in exchange for preparing the application. I see IP venture companies buying up patent applications for little more (or little less) than it would cost a reasonably priced practitioner to write the application. So, 100% to the attorney would not seem unreasonable in comparison to what the attorney would reasonably charge at an hourly rate.
Ah, but every inventor out there believes their invention is worth millions -- billions! And, (no offense to the original poster to this topic, but we here it nearly every day), the invention will simply sell itself. So, perhaps even 10% is unconscionable (obscenely unfair -- the kind of compensation attorneys can't take).
The problem is that, on the open market today, it's extremely rare for any single patent to sell outright for a million dollars. What that means is that, very smart people who evaluate odds and markets and IP value for a living, determine that the most a patent is worth -- in and of itself given all the risks and possible advantages -- is about a million dollars. While I don't follow the market as closely as some, I'd be very surprised to see a patent application go for more than a quarter of that. A sizeable percentage of that could still be not unreasonable given what some larger firms charge for writing ordinary patent applications. So, it would be extremely difficult to show just about any percentage of proceeds from a patent in exchange for writing the application would be reasonable compensation.
Of course, from what I understand, some courts will stick their hands in there and give money back to the client if, despite all the odds which made recovery of any compensation at all unlikely, the total payout after the odds have been played out turns out to be an unusually large number. Consider the California lottery as an example. The odds of winning are somewhat less than being struck by lightning twice -- something like 83million to 1. I think the jackpot tends to hover around half that number -- 40million or so. So, anyone with reasonable math skills would say -- bad investment: expected return on your dollar is about 50 cents. Simple probabilities. However, when someone wins, it always seems like a good investment after the fact. But it wasn't; the payout was not sufficiently large to justify the risk -- for anyone sort of into math and understanding probabilities.
So, I hope courts take the level of risk into consideration when reviewing reasonableness of compensation and that courts are even just moderately okay with math.
The problem is that it's extremely difficult to wrap one's mind around events with extremely low probabilities. Unfortunately, I think profiting largely and obscenely from an idea is one of those events.
Regards.