Short-term:

At this point if time it is reputation based - the only way to police is to give ratings like (5 star or 1 star) on the resolution of the market. Always be wary of new user created markets.

Long-term:

Meanwhile, I've been working on non-custodial markets, once I achieve some success, we'll add oracle functionality to market resolutions.

My initial plan is to have few (around 21) trusted oracles on Predyx like @grayruby, @Undisciplined and yourself @BlokchainB and more. The market resolution must receive at least 11 oracle's vote for it to resolve.