As an alternative to the shelling coin...
What if, when creating a prediction market, you include a list of yes_addresses, and a list of no_addresses.
The only people who can buy shares of YES are in the yes_addresses list. The only people who can buy shares of NO are in the no_addresses list.
Assuming that everyone already has a publicly available truthcoin address, you can make the no_addresses be the jury, and judge, and lawyers. The yes_address should be only yourself.
Also, no one should be able to sell shares of either type until the decisions are settled.
The only person who profits if you go to jail is yourself. If you go free, then they jury, and judge, and lawyers could profit.
Cryptographers are making better addresses. If you know Bobs's address, you can make a new random-looking address out of it that sends money to Bob. No one can tell that the random-looking address is owned by Bob, except for you and Bob.